Italian translation updated
Merge pull request #287 from bartokk/master

Italian translation updated
Add Greek (el_GR) translation
Add el_GR translation files
minor adjustments to translated strings.
Update Greek translation.
Remove Greek .mo
Merge pull request #288 from jinxos/gr_translation

Greek translation (el_GR)
usermanual: a bunch of minor corrections and updates
GTK3: Use accessor functions instead of direct access

GTK+ 3 removes many implementation details and struct members from its public headers.

Quote:
While it may be painful to convert, this helps us keep API and ABI compatibility when we change internal interfaces.

See https://developer.gnome.org/gtk3/3.9/gtk-migrating-2-to-3.html#id-1.6.3.3.5