implement pybullet.getContactPointData(), two optional object unique ids as filter

returns a pylist of contact points. Each point has the following data:

	0     int m_contactFlags;//unused for now
         1     int m_bodyUniqueIdA;
         2     int m_bodyUniqueIdB;
         3     int m_linkIndexA;
         4     int m_linkIndexB;
         5-6-7     double m_positionOnAInWS[3];//contact point location on object A, in world space coordinates
         8-9-10     double m_positionOnBInWS[3];//contact point location on object A, in world space coordinates
         11-12-13     double m_contactNormalOnBInWS[3];//the separating contact normal, pointing from object B towards object A
         14     double m_contactDistance;//negative number is penetration, positive is distance.

         15    double m_normalForce;

src/BulletDynamics/ConstraintSolver/btSequentialImpulseConstraintSolver.cpp

@@ -1053,8 +1053,8 @@ void	btSequentialImpulseConstraintSolver::convertContact(btPersistentManifold* m
 
 			if ((cp.m_combinedRollingFriction>0.f) && (rollingFriction>0))
 			{
-				//only a single rollingFriction per manifold
-				rollingFriction--;
+//disabled: only a single rollingFriction per manifold
+//				rollingFriction--;
 				if (relAngVel.length()>infoGlobal.m_singleAxisRollingFrictionThreshold)
 				{
 					relAngVel.normalize();