Recent versions of Gettext are able to translate several formats
that are used in GNOME applications. This patch migrates from
Intltool to Gettext by using meson's i18n features.
https://bugzilla.gnome.org/show_bug.cgi?id=787588
With the old shell gone, there is no need to work around cut off panel
names (bug #647087). As it stands now, it only confuses translators
(invisible characters are hard to, well, see).
https://bugzilla.gnome.org/show_bug.cgi?id=792629
Since we don't maintain two different shells anymore, there
is no need to maintain the two different sets of categories
in the desktop files.
This commit also drops the "#ifdef CC_ENABLE_ALT_CATEGORIES"
blocks, since the previous commit removed that define.
https://bugzilla.gnome.org/show_bug.cgi?id=790923
