Fix a typo
Updated Spanish translation
Update TODO
Updated Portuguese translation
Updated Greek translation
Adding 3.14 and 3.16 version targets to the GTK+ plugin

Updated GTK+ widget catalog for new properties and signals

Updated for GTK+ 3.14 and 3.16 (so far), this patch also modifies
the scrolled window editor to place the overlay-scrollbars property
nicely into the custom editor.

Also set GtkSidebar target version 3.16 (we dont encode odd numbers here)
fixup