Found reasonable OK solution for a cyclic dependency that was bothering
a lot of (character) animators. They would like to drive bones with
Objects, but that lagged when you parent these Objects to the
armature, since that's a circular dependency.
Since Driver relations are only looking at local object properties (i.e.
it's local position/rotation) there's a simple way to solve it. In case
such Objects have an Ipo, it reads driver values directly from the
Object Ipo (on correct time) instead of Object values.
03a1ee30b6