static objects by more restrictive selection of objects that collide
with static objects.
Rename collision mask fuctions from 'filter' to 'group' so it is clear
what is being set.
Rename BulletSimAPI.SetCollisionFilterMask() to SetCollisionGroupMask to match above.
Restore passing of time step to linear and angular motion component routines.
Use buffering vehicle physical parameter get/set routines consistantly.
Make range enforcement clearer by using ClampInRange() function for parameter setting.
Remove commented out experimental vehicle calculations.
