Blender Git Loki

Effector calculations are now thread safe.
* where_is_object_time was called for every effector evaluation only to determine the object velocity in some rare cases.
* Calculating the effector velocity is now done in the effector precalculation stage.
* Removing this makes the code thread safe and also should give some nice performance boosts when simulating a lot of points.
* Thanks to MiikaH for noticing this problem.