installer: Add Emacs EXWM desktop environment.

Suggested by zenny via IRC.

* gnu/installer/services.scm (%system-services): Add emacs, emacs-exwm,
emacs-desktop-environment.
* etc/release-manifest.scm (%system-packages): Likewise.
* gnu/system/examples/lightweight-desktop.tmpl: Likewise.
* gnu/tests/install.scm (installation-target-desktop-os-for-gui-tests)
[packages]: Likewise
* gnu/installer/newt/services.scm (run-desktop-environments-cbt-page): Make
one entry taller.

etc/release-manifest.scm

@@ -1,5 +1,6 @@
 ;;; GNU Guix --- Functional package management for GNU
 ;;; Copyright © 2020 Ludovic Courtès <ludo@gnu.org>
+;;; Copyright © 2020 Jan (janneke) Nieuwenhuizen <janneke@gnu.org>
 ;;;
 ;;; This file is part of GNU Guix.
 ;;;
@@ -53,6 +54,7 @@ TARGET."
   (append (map specification->package
                '("xorg-server" "xfce" "gnome" "mate" "enlightenment"
                  "openbox" "awesome" "i3-wm" "ratpoison"
+                 "emacs" "emacs-exwm" "emacs-desktop-environment"
                  "xlockmore" "slock" "libreoffice"
                  "connman" "network-manager" "network-manager-applet"
                  "openssh" "ntp" "tor"

gnu/installer/newt/services.scm

@@ -1,6 +1,7 @@
 ;;; GNU Guix --- Functional package management for GNU
 ;;; Copyright © 2018 Mathieu Othacehe <m.othacehe@gmail.com>
 ;;; Copyright © 2019 Ludovic Courtès <ludo@gnu.org>
+;;; Copyright © 2020 Jan (janneke) Nieuwenhuizen <janneke@gnu.org>
 ;;;
 ;;; This file is part of GNU Guix.
 ;;;
@@ -40,7 +41,7 @@ choose the one to use on the log-in screen.")
      #:items items
      #:selection (map system-service-recommended? items)
      #:item->text system-service-name             ;no i18n for DE names
-     #:checkbox-tree-height 8
+     #:checkbox-tree-height 9
      #:exit-button-callback-procedure
      (lambda ()
        (raise

gnu/installer/services.scm

@@ -1,6 +1,7 @@
 ;;; GNU Guix --- Functional package management for GNU
 ;;; Copyright © 2018 Mathieu Othacehe <m.othacehe@gmail.com>
 ;;; Copyright © 2019 Ludovic Courtès <ludo@gnu.org>
+;;; Copyright © 2020 Jan (janneke) Nieuwenhuizen <janneke@gnu.org>
 ;;;
 ;;; This file is part of GNU Guix.
 ;;;
@@ -82,6 +83,11 @@
       (name "ratpoison")
       (packages '((specification->package "ratpoison")
                   (specification->package "xterm"))))
+     (desktop-environment
+      (name "Emacs EXWM")
+      (packages '((specification->package "emacs")
+                  (specification->package "emacs-exwm")
+                  (specification->package "emacs-desktop-environment"))))
 
      ;; Networking.
      (system-service

gnu/system/examples/lightweight-desktop.tmpl

@@ -4,7 +4,8 @@
 
 (use-modules (gnu) (gnu system nss))
 (use-service-modules desktop)
-(use-package-modules bootloaders certs ratpoison suckless wm xorg)
+(use-package-modules bootloaders certs emacs emacs-xyz ratpoison suckless wm
+                     xorg)
 
 (operating-system
   (host-name "antelope")
@@ -43,6 +44,7 @@
   (packages (append (list
                      ;; window managers
                      ratpoison i3-wm i3status dmenu
+                     emacs emacs-exwm emacs-desktop-environment
                      ;; terminal emulator
                      xterm
                      ;; for HTTPS access

gnu/tests/install.scm

@@ -35,6 +35,8 @@
   #:use-module (gnu packages bootloaders)
   #:use-module (gnu packages commencement)       ;for 'guile-final'
   #:use-module (gnu packages cryptsetup)
+  #:use-module (gnu packages emacs)
+  #:use-module (gnu packages emacs-xyz)
   #:use-module (gnu packages linux)
   #:use-module (gnu packages ocr)
   #:use-module (gnu packages openbox)
@@ -1271,7 +1273,8 @@ build (current-guix) and then store a couple of full system images.")
     ;; graphical installer are available.
     (packages (append
                (list openbox awesome i3-wm i3status
-                     dmenu st ratpoison xterm)
+                     dmenu st ratpoison xterm
+                     emacs emacs-exwm emacs-desktop-environment)
                %base-packages))
     (services
      (append