* emacs/guix-main.scm (%licenses): New variable.
(licenses, license-names, lookup-license, lookup-license-uri): New
procedures.
* emacs/guix-read.el (guix-license-names, guix-read-license-name): New
procedures.
* emacs/guix-license.el: New file.
(guix-lookup-license-url): New procedure.
(guix-browse-license-url): New command.
* emacs.am (ELFILES): Add new file.
* emacs/guix-utils.el (guix-keyword-args-let): New macro.
(guix-utils-font-lock-keywords): Add it.
* emacs/guix-base.el (guix-define-buffer-type): Use it.
* emacs/guix-list.el (guix-list-define-entry-type): Use it.
* emacs/guix-read.el (guix-define-readers): Use it.
