Acrobatics: cosmetic changes
Acrobatics: do not touch modified stats
Acrobatics: use calculated fatigueTerm
Acrobatics: reinit fall height at current height rather than zero

To prevent problems.
Add MWWorld::isSlowFalling(Ptr)
Acrobatics: do not apply fall damages when slowfalling spell effect is active

If spell effect ends up in mid-air, calculate fall height from then.