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.

Introduce the 'GUIX_PACKAGE_PATH' environment variable.

* gnu/packages.scm (%package-module-path): Honor $GUIX_PACKAGE_PATH.
* test-env.in: Unset 'GUIX_PACKAGE_PATH'.
* tests/guix-package.sh: Test it.
* doc/guix.texi (Package Modules): Document it.

guix build: Add -L/--load-path as a common option.

* guix/scripts/build.scm (show-build-options-help): Document -L.
  (%standard-build-options): Add -L/--load-path.
* tests/guix-package.sh: Test it.

services: Add 'bitlbee-service'.

* gnu/services/networking.scm (bitlbee-service): New procedure.
* doc/guix.texi (Networking Services): Document it.

linux-initrd: Adjust VM code and doc to new 'base-initrd' signature.

This fixes regressions introduced in de1c158 ("system: Add support for
boot-time mapped devices.").

* doc/guix.texi (Initial RAM Disk): Adjust example with custom use of
  'base-initrd'.  Document #:mapped-devices parameter of 'base-initrd'.
* gnu/system/vm.scm (system-disk-image, system-qemu-image,
  virtualized-operating-system): Adjust call to 'base-initrd' to new
  signature.

doc: Remove a couple of limitations.

* doc/guix.texi (System Installation): Remove encrypted disks and swap
  from the limitations.

doc: Document mapped devices.

* doc/guix.texi (Mapped Devices): New subsection.

services: Add 'dhcp-client-service'.

* gnu/services/networking.scm (dhcp-client-service): New procedure.
* doc/guix.texi (Networking Services): Document it.

doc: Mention audio, video, and cdrom groups more prominently.

* doc/guix.texi (User Accounts): Add the "audio", "video", and "cdrom"
  groups in the example.

Merge branch 'master' into core-updates

Conflicts:
	gnu/packages/image.scm

linux-initrd: Store Linux modules in a normal store directory.

* gnu/system/linux-initrd.scm (expression->initrd): Remove #:linux and
  #:linux-modules parameters.  Remove call to
  'float-linux-module-directory'.
  (base-initrd): Add call to 'float-linux-module-directory'.  Use it in
  #:linux-modules argument in the gexp.  Remove #:linux and
  #:linux-modules arguments to 'expression->initrd'.
* gnu/build/linux-initrd.scm (build-initrd): Remove
  #:linux-module-directory parameter.  Don't create 'modules'
  sub-directory.
* gnu/build/linux-boot.scm (boot-system): Mentin that LINUX-MODULES is a
  list of absolute file names.  Don't prepend "/modules/" to
  LINUX-MODULES.
* doc/guix.texi (Initial RAM Disk): Adjust accordingly.

linux-initrd: Remove #:to-copy argument of 'expression->initrd'.

* gnu/system/linux-initrd.scm (expression->initrd): Remove #:to-copy
  parameter.  Remove 'graph-files', and adjust #:references-graphs
  arguments to just list INIT.
  (base-initrd): Remove #:to-copy argument.
* doc/guix.texi (Initial RAM Disk): Adjust accordingly.

emacs: Improve key bindings for marking the packages.

Use "U" to upgrade the current package, "^" to upgrade all.

* emacs/guix-list.el: (guix-list-unmark): With prefix, mark all.
  (guix-package-list-mark-outputs): New procedure.
  (guix-package-list-mark-install, guix-package-list-mark-delete)
  (guix-package-list-mark-upgrade): Use it.
  (guix-package-list-mark-upgrades): New command.
* doc/emacs.texi (emacs List buffer): Update the manual accordingly.

Merge branch 'master' into core-updates

gexp: Allow use of high-level objects in #:references-graphs.

* guix/gexp.scm (lower-reference-graphs): New procedure.
  (gexp->derivation)[graphs-file-names]: New procedure.
  Use 'lower-reference-graphs', and augment #:inputs argument as a
  function of #:references-graphs.
* doc/guix.texi (G-Expressions): Adjust 'gexp->derivation' documentation
  accordingly.
* tests/gexp.scm ("gexp->derivation, store copy"): Remove reference to
  TWO in BUILD-DRV.  Use TWO directly in #:references-graphs argument.
  ("gexp->derivation #:references-graphs"): New test.
* gnu/system/vm.scm (qemu-image): Remove variable 'graph'; use INPUTS as
  the #:references-graphs argument to
  'expression->derivation-in-linux-vm'.

Add Emacs user interface.

* configure.ac (emacsuidir): New variable.
  (AC_CONFIG_FILES): Add 'emacs/guix-init.el', 'emacs/guix-helper.scm'.
* Makefile.am: Include 'emacs.am'.
* emacs.am: New file.
* doc/emacs.texi: New file.
* doc/guix.texi: Include 'emacs.texi'.
* emacs/guix-backend.el: New file.
* emacs/guix-base.el: New file.
* emacs/guix-helper.scm.in: New file.
* emacs/guix-history.el: New file.
* emacs/guix-info.el: New file.
* emacs/guix-init.el.in: New file.
* emacs/guix-list.el: New file.
* emacs/guix-main.scm: New file.
* emacs/guix-utils.el: New file.
* emacs/guix.el: New file.

scripts: add guix lint

* guix/scripts/lint.scm: New file. Defines a 'lint' tool for Guix packages.
* tests/lint.scm: New file.
* Makefile.am (MODULES, SCM_TESTS): Add them.
* po/guix/Makevars: Update appropriately.
* po/guix/POTFILES.in: Update appropriately.
* doc/guix.texi: Document "guix lint".

doc: Clarify system installation and configuration details.

Reported by leth on #guix.

* doc/guix.texi (System Installation): Suggest running 'reboot' instead
  of 'umount /mnt'.
  (Initial RAM Disk): Add xref to SRFI-26.

daemon: Rename '--disable-store-optimization' to '--disable-deduplication'.

* nix/nix-daemon/guix-daemon.cc (GUIX_OPT_DISABLE_STORE_OPTIMIZATION):
  Rename to...
  (GUIX_OPT_DISABLE_DEDUPLICATION): ... this.  Adjust user accordingly.
  (options): Add "disable-deduplication".  Make
  "disable-store-optimization" a hidden alias.
* doc/guix.texi (Invoking guix-daemon): Adjust to new option name.  Add
  index entry.  Improve description.

Merge branch 'master' into core-updates

Conflicts:
	gnu/packages/base.scm