Add libhandy to adapt to smaller screens

Developed by Purism at https://source.puri.sm/Librem5/libhandy

Documentation at https://honk.sigxcpu.org/projects/libhandy/doc/

app.briar.gtk.json

@@ -80,6 +80,25 @@
                 }
             ]
         },
+        {
+            "name" : "libhandy",
+            "buildsystem" : "meson",
+            "config-opts": [
+                "-Dtests=false",
+                "-Dexamples=false",
+                "-Dgtk_doc=false",
+                "-Dvapi=false",
+                "-Dglade_catalog=disabled"
+            ],
+            "sources" : [
+                {
+                    "type" : "git",
+                    "tag" : "v0.0.13",
+                    "url" : "https://source.puri.sm/Librem5/libhandy.git"
+                }
+            ]
+        },
+
         {
             "name": "briar-headless",
             "buildsystem": "simple",

briar-gtk/briar_gtk/application.py

@@ -9,7 +9,8 @@
 import gi
 gi.require_version('Gdk', '3.0')
 gi.require_version('Gtk', '3.0')
-from gi.repository import Gdk, Gio, GLib, Gtk
+gi.require_version('Handy', '0.0')
+from gi.repository import Gdk, Gio, GLib, Gtk, Handy
 
 from briar_wrapper.api import Api
 
@@ -30,6 +31,7 @@ class Application(Gtk.Application, ApplicationActions):
     def do_startup(self):
         Gtk.Application.do_startup(self)
         Application._setup_styling(APPLICATION_STYLING_PATH)
+        Handy.init()
         self._setup_api()
 
     # pylint: disable=arguments-differ

meson.build

@@ -10,4 +10,5 @@ project(
 
 i18n = import('i18n')
 
+dependency('libhandy-0.0')
 subdir('briar-gtk')