add getClosestPoints.py example.

allow to perform a getClosestPoints query with a collisionShape and world transform (position, orientation) that isn't part of the world.
(use createCollisionShape to create it)
add optional removeCollisionShape, for collision shapes only used in a query (and not used to create a body)

examples/SharedMemory/SharedMemoryCommands.h

@@ -615,6 +615,8 @@ struct b3ObjectArgs
     int m_bodyUniqueIds[MAX_SDF_BODIES];
 	int m_numUserConstraints;
 	int m_userConstraintUniqueIds[MAX_SDF_BODIES];
+	int m_numUserCollisionShapes;
+	int m_userCollisionShapes[MAX_SDF_BODIES];
 };
 
 struct b3Profile