BulletSim: Add physical 'actors' that operate on the physical object.
Add first 'actor' for locked axis.
BulletSim: convert BSDynamic to a BSActor and change BSPrim to set
up the vehicle actor.
BulletSim: fix line endings in BSActor*
BulletSim: start the renaming of local variables to m_ form to match the OpenSim coding conventions.
BulletSim: not quite functional axis lock code.
BulletSim: stop an avatar from moving if standing on a stationary
object. This will stop avatars from sliding down steep terrains
or objects while still allowing an avatar to be moved if standing
on a moving object.