EMI: Animation fixes

A head start on GSoC tasks :)

5a95dfd fixes a bug in the interpolation between key frame positions that caused animations to appear jerky. Very noticeable everywhere, but for example Guybrush's walk cycle is much smoother now.

ef58564 implements handling for key values 1 and 3 of the anim component. This fixes incorrect repetition of animations that are meant to play only once. Noticeable for example in inventory animations and the catapult and its operator in gme.set.

StopChore may be called from Lua without a time parameter. Such calls were previously ignored. Fixed by 7355af8. This commit also improves the catapult in gme.set.