Revert "Bug #840, First Person Sneaking Camera Height"

This reverts commit 296abfd48faec66aa77490f58d6f0e868bb4f17f.
Refactored, moved logic out of NpcAnimation

The logic is now handled by RenderingManager, and Camera sets its
animation's first person offset height. Due to how NpcAnimation seems to
be updated, it has to be the one to actually set its own nodes, in the
case of the hands. Otherwise, the hands would not move without a messier
hack.