Reported by Ludovic Courtès <ludo@gnu.org> on #guix.
This fixes a regression introduced in commit 7171d824.
'insert-text-button' procedure does not allow to override a button face,
so a specialized button type should be used instead.
* emacs/guix-ui-package.el (guix-package-heading): New button type.
(guix-package-info-insert-heading): Use it.
* emacs/guix-ui-package.el (guix-package-list-latest-builds): New
procedure.
(guix-package-list-mode-map): Bind "B" key to it.
(guix-output-list-mode-map): Likewise.
* doc/emacs.texi (Emacs List buffer): Document it.
* emacs/guix-ui.el (guix-ui-read-profile): New procedure.
* emacs/guix-ui-package.el (guix-search-by-name)
(guix-search-by-regexp, guix-installed-packages)
(guix-obsolete-packages, guix-all-available-packages)
(guix-newest-available-packages): Use it.
* emacs/guix-ui-generation.el (guix-generations)
(guix-last-generations, guix-generations-by-time): Use it.
* emacs/guix-buffer.el (guix-define-groups, guix-define-entry-type)
(guix-define-buffer-type): New macros.
(guix-buffer-define-interface): Add parent groups for the generated
custom groups.
* emacs/guix-info.el: Use 'guix-define-buffer-type' to generate custom
groups.
* emacs/guix-list.el: Likewise.
* emacs/guix-ui.el: Use 'guix-define-groups' to generate custom groups.
(guix-ui-define-entry-type): New macro.
* emacs/guix-ui-package.el: Use it.
* emacs/guix-ui-generation.el: Use it.
Alex Kost