This patch implements a custom widget that can switch its texture on-the-fly, making it obsolete having to use an atlas to get a hover animation. This also removes the predefined size restriction and should now work with all button texture sizes.
I made a bunch of changes in apps/openmw/mwrender/animation.cpp
because the scope brackets didn't line up in a bunch of places
npcanimations.cpp & creatureanimations.cpp were the same kind of
thing