Merge branch 'master' into core-updates

guix package: Allow multiple '--search' flags.

* guix/scripts/package.scm (find-packages-by-description): Change 'rx'
parameter to 'regexps'.
[matches-all?, matches-one?]: New procedures.
Use them.
(process-query): Collect regexps from all 'search' queries, and pass
them to 'find-packages-by-description'.
* tests/guix-package.sh: Add tests.
* doc/guix.texi (Invoking guix package): Document it.

Merge branch 'master' into core-updates

guix package: Fix typo in comment.

* guix/scripts/package.scm: Fix typo.

Merge branch 'master' into core-updates

guix package: Refactor 'options->installable'.

* guix/scripts/package.scm (options->upgrade-predicate)
(store-item->manifest-entry): New procedures.
* guix/scripts/package.scm (options->installable): Use them.  Remove the
'packages-to-upgrade' and 'packages-to-install' variables by getting rid
of a level of indirection.

guix package: Move 'process-actions' out of sight.

* guix/scripts/package.scm (process-actions): New procedure, moved
from...
(guix-package): ... here.  Adjust accordingly.

guix package: Formalize the list of actions.

* guix/scripts/package.scm (roll-back-action, switch-generation-action)
(delete-generations-action, manifest-action): New procedures.
(%actions): New variable.
* guix/scripts/package.scm (guix-package)[process-action]: Rewrite to
traverse %ACTIONS.

guix package: Move 'build-and-use-profile' out of sight.

* guix/scripts/package.scm (build-and-use-profile): New procedure.
Adapted and moved from...
(guix-package)[process-actions]: ... here.  Adjust call sites.

guix package: Move a couple of procedures out of sight.

* guix/scripts/package.scm (ensure-default-profile, process-query): New
procedures, moved from...
(guix-package): ... here.

guix package: Remove unnecessary use of (%store).

* guix/scripts/package.scm (delete-matching-generations): Use STORE
instead of (%store).

guix package: Reduce startup time by ~50%.

As measured with:

  time sh -c 'for i in `seq 1 10` ; do guix package --search-paths ; done'

On my machine, when running:

  strace -o ,,s guix package --search-paths

the number returned by:

  grep -E '^(open|l?stat).*\.go' ,,s | wc -l

drops from 1610 to 837.

* guix/scripts/package.scm: Remove two unnecessary #:use-module forms.
Autoload (gnu packages ...) modules.

guix package: '--search-paths' can report combined search paths.

Partly fixes <http://bugs.gnu.org/20255>.

* guix/scripts/package.scm (search-path-environment-variables): Change
  'profile' to 'profiles'; expect it to be a list.
  (display-search-paths): Likewise.
  (%default-options): Remove 'profile' entry.
  (%options) <--profile>: Keep previous values associated with 'profile'
  in RESULT.
  (guix-package)[process-actions, process-query]: Handle the possible
  lack of 'profile' pair in OPTS.

Merge branch 'master' into dbus-update

ui: Add 'make-regexp*'.

Fixes <http://bugs.gnu.org/21773>.
Reported by Jan Synáček <jan.synacek@gmail.com>.

* guix/ui.scm (make-regexp*): New procedure.
* guix/scripts/package.scm (options->installable, guix-package): Use it
  when processing user-provided regexps.

profiles: Add generation manipulation procedures.

* guix/scripts/package.scm (delete-generations): Use
  'delete-generation*' instead of 'delete-generation'.
  (guix-package)[process-actions]: Use 'roll-back*' instead of
  'roll-back' and 'switch-to-generation*' instead of
  'switch-to-generation'.
  (link-to-empty-profile, switch-to-generation,
  switch-to-previous-generation, roll-back, delete-generation): Move
  to...
* guix/profiles.scm: ... here.  Adjust to not print messages and to
  return values that can be used by user interfaces.
* guix/ui.scm (display-generation-change, roll-back*,
  switch-to-generation*, delete-generation*): New procedures.

ui: Add procedures to display a profile generation.

* guix/scripts/package.scm (guix-package)[process-query](list-generations):
  Move part of the body to 'delete-generation' and
  'display-profile-content'.
* guix/ui.scm (display-generation, display-profile-content): New
  procedures.

utils: Add 'readlink*'.

* guix/scripts/package.scm (readlink*): Move to...
* guix/utils.scm (readlink*): ... here.  New procedure.

ui: Add 'matching-generations'.

* guix/scripts/package.scm (matching-generations): Move to...
* guix/ui.scm (matching-generations): ... here.

Merge branch 'master' into core-updates