Add version-compare and version>? to utils.scm.

* guix/utils.scm (version-compare, version>?): New exported procedures,
  based on version-string>?, which was formerly in gnu-maintenance.scm.

* guix/gnu-maintenance.scm (version-string>?): Removed procedure.
  (latest-release): Use 'version>?' instead of 'version-string>?'.

Add version-compare and version>? to utils.scm.

* guix/utils.scm (version-compare, version>?): New exported procedures,
  based on version-string>?, which was formerly in gnu-maintenance.scm.

* guix/gnu-maintenance.scm (version-string>?): Removed procedure.
  (latest-release): Use 'version>?' instead of 'version-string>?'.

gnu-maintenance: Add `latest-release' and related tools.

* guix/gnu-maintenance.scm (ftp-server/directory, releases,
  version-string>?, latest-release, gnu-package-name->name+version): New
  procedures.
  (%package-name-rx): New variable.

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.

Merge branch 'master' into nix-integration

Conflicts:
	guix/store.scm

Add (guix gnu-maintenance).

* guix/gnu-maintenance.scm: New file.
* Makefile.am (MODULES): Add it.