ui: Add `args-fold*' and use it.

* guix/ui.scm (args-fold*): New procedure.
* guix/scripts/build.scm, guix/scripts/download.scm,
  guix/scripts/gc.scm, guix/scripts/hash.scm, guix/scripts/import.scm,
  guix/scripts/package.scm, guix/scripts/pull.scm,
  guix/scripts/refresh.scm: Use `args-fold*' instead of `args-fold'.

scripts: Remove hyphen in the command name shown by `--version'.

* guix/scripts/build.scm (%options): Remove hyphen from the name passed
  to `show-version-and-exit'.
* guix/scripts/download.scm (%options): Likewise.
* guix/scripts/gc.scm (%options): Likewise.
* guix/scripts/import.scm (%options): Likewise.
* guix/scripts/package.scm (%options): Likewise.

scripts: Remove initialization now redundant with `initialize-guix'.

* guix/scripts/build.scm (guix-build): Remove calls to `install-locale',
  `textdomain', etc., now redundant with `initialize-guix'.
* guix/scripts/download.scm (guix-download): Likewise.
* guix/scripts/import.scm (guix-import): Likewise.
* guix/scripts/package.scm (guix-package): Likewise.
* guix/ui.scm: Remove export of `install-locale' and `initialize-guix'.
  (initialize-guix): Add docstring.

Replace individual scripts with master 'guix' script.

* scripts/guix.in: New script.

* Makefile.am (bin_SCRIPTS): Add 'scripts/guix'.  Remove 'guix-build',
  'guix-download', 'guix-import', 'guix-package', and 'guix-gc'.

  (MODULES): Add 'guix/scripts/build.scm', 'guix/scripts/download.scm',
  'guix/scripts/import.scm', 'guix/scripts/package.scm', and
  'guix/scripts/gc.scm'.

* configure.ac (AC_CONFIG_FILES): Add 'scripts/guix'.  Remove 'guix-build',
  'guix-download', 'guix-import', 'guix-package', and 'guix-gc'.

* guix-build.in, guix-download.in, guix-gc.in, guix-import.in,
  guix-package.in: Remove shell script boilerplate.  Move to guix-COMMAND.in
  to guix/scripts/COMMAND.scm.  Rename module from (guix-COMMAND) to
  (guix scripts COMMAND).  Change "guix-COMMAND" to "guix COMMAND" in
  usage help string.

* pre-inst-env.in: Add "@abs_top_builddir@/scripts" to the front of $PATH.
  Export $GUIX_UNINSTALLED.

* tests/guix-build.sh, tests/guix-daemon.sh, tests/guix-download.sh,
  tests/guix-gc.sh, tests/guix-package.sh: Use "guix COMMAND" instead of
  "guix-COMMAND".

* doc/guix.texi: Replace all occurrences of "guix-COMMAND" with
  "guix COMMAND".

* po/POTFILES.in: Update.

Gracefully handle failure to install the current locale.

* guix/ui.scm (install-locale): New procedure.
* guix-build.in, guix-download.in, guix-gc.in, guix-import.in,
  guix-package.in: Use it instead of (setlocale LC_ALL "").

Merge branch 'master' into core-updates

Conflicts:
	build-aux/download.scm
	distro/packages/autotools.scm
	distro/packages/base.scm
	distro/packages/bootstrap.scm
	distro/packages/lsh.scm
	distro/packages/make-bootstrap.scm
	distro/packages/ncurses.scm
	distro/packages/perl.scm
	tests/derivations.scm
	tests/union.scm

Update license headers.

Change all license headers, except guix/build/* and ld-wrapper.scm, with
this code:

  (use-modules (guix build utils)
	       (srfi srfi-1))

  (fluid-set! %default-port-encoding "UTF-8")

  (substitute* (remove (lambda (f)
			 (or (string-contains f ".tar.")
			     (string-contains f ".git/")
			     (string-contains f ".so")
			     (string-suffix? ".o" f)
			     (string-suffix? ".a" f)
			     (string-suffix? ".go" f)
			     (string-suffix? ".pdf" f)
			     (string-suffix? ".png" f)
			     (string-suffix? ".info" f)
			     (equal? (basename f) "guix-daemon")
			     (equal? (basename f) "nix-setuid-helper")
			     (string-contains f "nix-upstream/")
			     (string-contains f "distro/packages/bootstrap/")))
		       (find-files "." "\\.[a-z]+$"))
    (("^([[:graph:]]+) This file is part of Guix." _ comment-start)
     (string-append comment-start " This file is part of GNU Guix."))
    (("^([[:graph:]]+) Guix --- Nix package management.*" _ comment-start)
     (string-append comment-start
		    " GNU Guix --- Functional package management for GNU\n"))
    (("^([[:graph:]]+) Guix is " _ comment-start)
     (string-append comment-start " GNU Guix is "))
    (("^([[:graph:]]+) along with Guix." _ comment-start)
     (string-append comment-start " along with GNU Guix."))
    (("^([[:graph:]]+) Copyright \\(C\\)" _ comment-start)
     (string-append comment-start " Copyright ©")))

Change headers using C-style comments manually.

ui: Factorize bug-report information in `--help'.

* guix/config.scm.in (%guix-home-page-url): New variable.
* guix/ui.scm (show-bug-report-information): New procedure.
* guix-build.in (show-help): Use it.
* guix-download.in (show-help): Likewise.
* guix-import.in (show-help): Likewise.
* guix-package.in (show-help): Likewise.

Add (guix snix) and the `guix-import' command.

* guix/snix.scm, tests/snix.scm, guix-import.in: New files.
* configure.ac: Output `guix-import' and make it executable.
* Makefile.am (bin_SCRIPTS): Add `guix-import'.
  (MODULES): Add `guix/snix.scm'.
  (TESTS): Add `tests/snix.scm'.