allow to use colors from MJCF file as option (default to random Google colors), use p.loadMJCF(filename, flags=p.URDF_MJCF_COLORS_FROM_FILE

fix quadruped.py example.
add PyBullet.isConnected() API, more friendly than PyBullet.getConnectionInfo()["connected"]

examples/SharedMemory/SharedMemoryPublic.h

@@ -674,6 +674,7 @@ enum eURDF_Flags
 	URDF_RESERVED=64,
 	URDF_USE_IMPLICIT_CYLINDER =128,
 	URDF_GLOBAL_VELOCITIES_MB =256,
+	MJCF_COLORS_FROM_FILE=512,
 };
 
 enum eUrdfGeomTypes //sync with UrdfParser UrdfGeomTypes