PyBullet: add option to cache graphics shapes for URDF files, handy for benchmarks with many duplicate robots

See https://github.com/erwincoumans/pybullet_robots ANYmal.py for an example.
PyBullet: Expose p.setPhysicsEngineParameter(solverResidualThreshold=1e-2) (b3PhysicsParamSetSolverResidualThreshold), increases solver performance a lot
PyBullet: Expose p.setPhysicsEngineParameter(contactSlop) Set it to zero, to avoid issues with restitution.
PyBullet: Expose isNumpyEnabled, return True is PyBullet was compiled with NUMPY support for 'getCameraImage'.
PyBullet: Expose p.ChangeDynamics(objectUid, linkIndex, contactProcessingThreshold), to avoid issues of speculative/predictive contacts with restitution.
See also http://twvideo01.ubm-us.net/o1/vault/gdc2012/slides/Programming%20Track/Vincent_ROBERT_Track_ADifferentApproach.pdf

examples/SharedMemory/SharedMemoryPublic.h

@@ -681,6 +681,7 @@ enum eURDF_Flags
 	URDF_USE_IMPLICIT_CYLINDER =128,
 	URDF_GLOBAL_VELOCITIES_MB =256,
 	MJCF_COLORS_FROM_FILE=512,
+	URDF_ENABLE_CACHED_GRAPHICS_SHAPES=1024,
 };
 
 enum eUrdfGeomTypes //sync with UrdfParser UrdfGeomTypes
@@ -755,6 +756,8 @@ struct b3PhysicsSimulationParameters
 	int m_deterministicOverlappingPairs;
 	double m_allowedCcdPenetration;
 	int m_jointFeedbackMode;
+	double m_solverResidualThreshold;
+	double m_contactSlop;
 };