Update default favorite apps list

Many of the apps in the favorite apps list have fallen out of favor.

Replacing Rhythmbox with Music and Shotwell with Photos are obvious
moves. Rhythmbox and Shotwell are not core apps, and that means we
assume they are not installed by default. It doesn't really make sense
to have non-default apps in the apps list.

Evolution is also not a core app, and that is not likely to change, so
it should also be removed. Adding Geary might be more controversial. It
is a strong candidate to become a core app, GNOME Mail, in the near
future, but it is not there yet. So this could arguably be considered
premature. But I figure a GSettings
default is a cheap thing; we can always change it later if desired.

Calendar is added at the request of GNOME design team ("replacing" the
calendar functionality of Evolution).

https://gitlab.gnome.org/GNOME/gnome-shell/merge_requests/907

data/org.gnome.shell.gschema.xml.in

@@ -50,7 +50,7 @@
       </description>
     </key>
     <key name="favorite-apps" type="as">
-      <default>[ 'org.gnome.Epiphany.desktop', 'org.gnome.Evolution.desktop', 'rhythmbox.desktop', 'org.gnome.Shotwell.desktop', 'org.gnome.Nautilus.desktop', 'org.gnome.Software.desktop' ]</default>
+      <default>[ 'org.gnome.Epiphany.desktop', 'org.gnome.Geary.desktop', 'org.gnome.Calendar.desktop', 'org.gnome.Music.desktop', 'org.gnome.Photos.desktop', 'org.gnome.Nautilus.desktop', 'org.gnome.Software.desktop' ]</default>
       <summary>List of desktop file IDs for favorite applications</summary>
       <description>
         The applications corresponding to these identifiers