Bump version to 3.14.0

Update NEWS.
window: Fix titlebar_is_onscreen() test

The titlebar rect is in window coordinates, while screen regions are
obviously not. Fix by translating into screen coordinates before
testing for overlaps.

https://bugzilla.gnome.org/show_bug.cgi?id=736915
constraints: Fix update_onscreen_requirements()

Another missing translation into screen coordinates ...

https://bugzilla.gnome.org/show_bug.cgi?id=736915