It is a fast way to keep track of overlapping objects in an area, and doing rayTest and convexSweepTest for overlapping objects, instead of btCollisionWorld::rayTest/convexSweepTest.
Updated KinematicCharacterController to use btPairCachingGhostObject.
It leads to problems with certain compilers, when Bullet/src is located in a long pathname.
Keep include path starting with "LinearMath/, "BulletCollision/, or "BulletDynamics/
CompoundShapes are tricky to manage with respect to persistent contact points and swapped order of btCollisionObjects,
During dispatch, finding an algorith etc. order can be swapped.
fixed several other issues, related to SimpleBroadphase (removing a proxy was not working)
