emacs: Add 'guix-pull' command.

* emacs/guix-base.el (guix-pull): New command.
  (guix-update-after-pull, guix-after-pull-hook): New variables.
  (guix-restart-repl-after-pull, guix-update-buffers-maybe-after-pull): New
  procedures.
* emacs/guix-main.scm: Use (guix scripts pull) module.
* doc/emacs.texi (Emacs Commands): Document 'guix-pull' command.

emacs: Improve REPL procedures.

* emacs/guix-backend.el (guix-start-process-maybe): Add 'start-msg' and
  'end-msg' optional arguments.
  (guix-start-repl-maybe): Likewise.  Do not kill buffer with a dead process.
  (guix-repl-exit): New procedure.
  (guix-eval-in-repl): Use 'geiser-repl--send'.

emacs: Improve buffer procedures.

* emacs/guix-base.el (guix-list-or-info-buffer-p): Delete.  Replace with...
  (guix-buffer-p): ... this.  New procedure.
  (guix-buffers): Use it.  Add 'modes' argument.
  (guix-update-buffer): New procedure.
  (guix-update-buffers-maybe): Rename to ...
  (guix-update-buffers-maybe-after-operation): this.  Use
  'guix-update-buffer'.

emacs: Introduce REPL operation type.

* emacs/guix-backend.el (guix-repl-operation-type): New variable.
  (guix-repl-output-filter): Run type hooks after performing an operation.
  (guix-eval-read): Add 'operation-type' argument.

emacs: Handle updating by ID after REPL restart.

* emacs/guix-base.el (guix-entry-to-specification,
  guix-entries-to-specifications): New procedures.
  (guix-revert-buffer): Search by name if searching by ID gives no results.

emacs: Improve interface for working with multiple profiles.

Suggested by David Thompson, Ludovic Courtès and Mathieu Lirzin.

* emacs/guix-base.el (guix-profile-prompt): New procedure.
  (guix-set-current-profile): Use it.
  (guix-buffer-name-simple, guix-buffer-name-default, guix-buffer-name): New
  procedures.
  (guix-buffer-name-function, guix-profile): New variables.
  (guix-set-vars, guix-get-entries, guix-get-show-entries, guix-set-buffer,
  guix-history-call, guix-process-package-actions,
  guix-continue-package-operation-p, guix-delete-generations,
  guix-switch-to-generation): Add 'profile' argument.
* emacs/guix.el (guix-get-show-packages, guix-get-show-generations,
  guix-search-by-name, guix-search-by-regexp, guix-installed-packages,
  guix-obsolete-packages, guix-all-available-packages,
  guix-newest-available-packages, guix-generations, guix-generations-by-time):
  Likewise.
  (guix-last-generations): New command.
* emacs/guix-info.el: Adjust for using 'profile' argument where needed.
* emacs/guix-list.el: Likewise.
* doc/emacs.texi (Emacs Commands): Document 'guix-last-generations' and using
  "C-u" for commands.
  (Emacs Buffer Names): Document 'guix-buffer-name-function'.

emacs: Add 'guix-generations-by-time' command.

* emacs/guix-main.scm (find-generations): Add finding generations by time.
* emacs/guix-utils.el (guix-read-date): New procedure.
* emacs/guix-base.el (guix-messages): Add new messages.
* emacs/guix.el (guix-generations-by-time): New command.
* doc/emacs.texi (emacs Commands): Document it.

emacs: Support auto-updating after performing REPL operation.

* emacs/guix-backend.el (guix-operation-buffer): New variable.
  (guix-eval-in-repl): Use it.  Add optional 'operation-buffer' argument.
* emacs/guix-base.el (guix-update-after-operation): New variable.
  (guix-switch-to-buffer, guix-list-or-info-buffer-p, guix-buffers,
  guix-update-buffers-maybe): New procedures.
  (guix-set-buffer): Use 'guix-switch-to-buffer'.  Add optional 'no-display'
  argument.
  (guix-process-package-actions, guix-delete-generations,
  guix-switch-to-generation): Add optional 'operation-buffer' argument.
* emacs/guix-info.el (guix-package-info-insert-action-button,
  guix-generation-info-insert-number, guix-generation-info-insert-current):
  Adjust for using operation buffer.
* emacs/guix-list.el (guix-list-execute-package-actions,
  guix-generation-list-switch, guix-generation-list-execute): Likewise.

emacs: Add hooks for REPL operations.

* emacs/guix-backend.el (guix-before-repl-operation-hook,
  guix-after-repl-operation-hook, guix-repl-operation-p): New variables.
  (guix-repl-operation-success-message, guix-repl-output-filter): New
  procedures.
  (guix-start-repl): Adjust for using 'guix-repl-output-filter'.
  (guix-eval-in-repl): Honor 'guix-before-repl-operation-hook'.

emacs: Add support for switching generations.

* emacs/guix-base.el (guix-switch-to-generation): New procedure.
* emacs/guix-info.el (guix-generation-info-insert-current): Insert button for
  switching to generation.
* emacs/guix-list.el (guix-generation-list-switch): New procedure.
* doc/emacs.texi (emacs List buffer, emacs Info buffer): Document switching
  generations.

emacs: Add 'current' generation parameter.

* emacs/guix-main.scm (generation-param-alist): Add 'current' parameter.
* emacs/guix-base.el (guix-param-titles): Add title for 'current' parameter.
* emacs/guix-info.el: Display 'current' parameter.
  (guix-generation-info-current, guix-generation-info-not-current): New faces.
  (guix-generation-info-insert-current): New procedure.
* emacs/guix-list.el: Display 'current' column.
  (guix-generation-list-get-current): New procedure.

emacs: Allow list functions to deal with nil values.

* emacs/guix-list.el (guix-list-get-tabulated-entry): Call functions returning
  column value even for nil values.
  (guix-list-get-one-line): Adjust for accepting nil argument.

ui: Move 'show-manifest-transaction' from (guix profiles).

* guix/profiles.scm: Do not use (guix ui) module.
  (right-arrow, manifest-show-transaction): Move and rename to...
* guix/ui.scm (right-arrow, show-manifest-transaction): ... here.
* tests/profiles.scm ("manifest-show-transaction"): Move to...
* tests/ui.scm ("show-manifest-transaction"): ... here.
  (guile-1.8.8, guile-2.0.9): New variables.
* emacs/guix-main.scm (process-package-actions): Rename
  'manifest-show-transaction' to 'show-manifest-transaction'.
* guix/scripts/package.scm (guix-package): Likewise.

Signed-off-by: Ludovic Courtès <ludo@gnu.org>

emacs: Use 'with-store' in 'process-package-actions'.

* emacs/guix-main.scm (process-package-actions): Use 'with-store'.

emacs: Add support for deleting generations.

* doc/emacs.texi (emacs List buffer): Mention new key bindings.
* emacs/guix-base.el (guix-delete-generations): New procedure.
* emacs/guix-info.el (guix-generation-info-insert-number): Use it.
* emacs/guix-list.el (guix-generation-list-mark-delete,
  guix-generation-list-execute): New procedures.
* emacs/guix-main.scm (delete-generations*): New procedure.

emacs: Add support for modifying options during operation confirmation.

* emacs/guix-base.el (guix-operation-option-key): New face.
  (guix-operation-option-true-string, guix-operation-option-false-string,
  guix-operation-option-separator, guix-operation-options): New variables.
  (guix-operation-option-by-key, guix-operation-option-key,
  guix-operation-option-name, guix-operation-option-variable,
  guix-operation-option-value, guix-operation-option-string-value,
  guix-operation-prompt, guix-operation-set-mode-line): New procedures.
  (guix-continue-package-operation-p): Use 'guix-operation-prompt'.

emacs: Use package/output type variables where needed.

* emacs/guix-list.el (guix-package-list-type, guix-output-list-describe-type):
  Move to...
* emacs/guix-base.el: ... here.  Rename 'guix-output-list-describe-type' to
  'guix-package-info-type'.
* emacs/guix-info.el (guix-generation-info-insert-number): Use
  'guix-package-list-type'.
* emacs/guix.el (guix-get-show-packages): Use 'guix-package-info-type'.

emacs: Support font-locking.

Avoid breaking highlighting after adding new font-lock keywords.

* emacs/guix-base.el (guix-insert-package-strings): Use 'propertize' instead
  of 'guix-get-string'.
* emacs/guix-info.el (guix, guix-action, guix-file, guix-url,
  guix-package-location, guix-package-name): New button types.
  (guix-info-insert-action-button, guix-info-insert-file-path,
  guix-info-insert-url, guix-package-info-insert-location,
  guix-package-info-insert-full-names,
  guix-package-info-insert-non-unique-text): Adjust for 'guix-insert-button'
  and button types.
  (guix-package-info-name-button): New face.
  (guix-package-info-define-insert-inputs): Use it.  Add new button types.
  (guix-package-info-insert-full-name): Remove.
* emacs/guix-utils.el (guix-get-string): Replace 'face' with 'font-lock-face'.
  (guix-insert-button): Adjust for using button types.

emacs: Fix errors in receiving information.

* emacs/guix-main.scm (package-pattern-transformer,
  output-pattern-transformer): Add fallback 'match' clauses.
  (find-generations): Fix getting generations by IDs.

emacs: Add support for displaying outputs.

Suggested by Taylan Ulrich Bayirli/Kammer and Ludovic Courtès.

* emacs/guix-base.el (guix-param-titles): Add output titles.
  (guix-messages): Add output messages.
  (guix-get-package-id-and-output-by-output-id): New procedure.
  (guix-define-buffer-type): Add ':buffer-name' key.
* emacs/guix-info.el: Add "output-info" buffer type.
  (guix-info-insert-methods): Add output methods.
  (guix-info-displayed-params): Add output params.
  (guix-output-info-insert-version, guix-output-info-insert-output): New
  procedures.
* emacs/guix-list.el: Add "output-list" buffer type.
  (guix-list-column-format): Add output formats.
  (guix-list-column-value-methods): Add output methods.
  (guix-package-list-type): New variable.
  (guix-generation-list-show-packages): Use it.
  (guix-package-list-marking-check): Use 'guix-output-list-mode'.
  (guix-list-mark-package-upgrades): New procedure.
  (guix-package-list-mark-upgrades): Use it.
  (guix-list-execute-package-actions): New procedure.
  (guix-package-list-execute): Use it.
  (guix-list-describe-maybe): New procedure.
  (guix-list-describe): Use it.
  (guix-output-list-mark-install, guix-output-list-mark-delete,
  guix-output-list-mark-upgrade, guix-output-list-mark-upgrades,
  guix-output-list-execute, guix-output-list-make-action,
  guix-output-list-describe): New procedures.
  (guix-output-list-describe-type): New variable.
* emacs/guix.el (guix-get-show-packages): Use 'guix-package-list-type'.
* doc/emacs.texi (emacs Commands): Mention 'guix-package-list-type'.
  (emacs List buffer): Adjust accordingly.
  (emacs Info buffer): Likewise.
  (emacs Buffer Names): New node.
  (emacs Keymaps): Add keymaps for output buffers.