add rolling/spinning friction to cube, remove it from plane/samurai.urdf
URDF2Bullet: support joint limits for revolute and prismatic, only if defined (if upper < lower, disable limit)
add some profiling markers to improve performance
URDF/SDF: add a flag to force concave mesh collisiofor static objects. <collision concave="yes" name="pod_collision">
VR: support teleporting using buttong, allow multiple controllers to be used, fast wireframe rendering,
Turn off warnings about deprecated C routine in btScalar.h/b3Scalar.h
Add a dummy return to stop a warning
Expose defaultContactERP in shared memory api/pybullet.
First start to expose IK in shared memory api/pybullet (not working yet)