tune gripper grasp example with tefal pan, 800Newton force.
URDF importer: if using single transform 1 child shape, don't use compound shape.
if renderGUI is false, don't intercept mouse clicks
add manyspheres.py example (performance is pretty bad, will look into it)
[pybullet] expose contactBreakingThreshold
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
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)
