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
rolling friction -> only along the normal, until we have separate rolling friction coefficients on normal and non-normal directions
Don't teleport with grasping controller (VR)
Tune VR grasping a bit.
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)
add wsg50 gripper with modified r2d2 gripper tip
expose a fudge factor to scale inertia, to make grasping more stable
(until we have better grasping contact model/implementation)
