Bump libgtk3 to 3.11.5.

The relevant patches are updated or discarded.
Add a package that installs DejaVu fonts

Some sort of fonts is required to properly render the glyphs in GTK applications.
DejaVu fonts are a start, but these can be changed later, if necessary.
Merge pull request #2 from zdobersek/libgtk3-update

libgtk3 update and add fonts