Expose pushProfileTimer / pop ProfileTimer in PhysicsClient API to benchmark Python parts of PyBullet.

reduce 'm_cooldownTime' from 1000 microseconds to 100 microseconds (overhead in raycast is too large)
If needed, we can expose this cooldown time.
Replace malloc by btAlignedObjectArray (going through Bullet's memory allocator)

src/BulletDynamics/ConstraintSolver/btSequentialImpulseConstraintSolver.cpp

@@ -781,7 +781,8 @@ int	btSequentialImpulseConstraintSolver::getOrInitSolverBody(btCollisionObject&
     else
     {
         // Incorrectly set collision object flags can degrade performance in various ways.
-        btAssert( body.isStaticOrKinematicObject() );
+        //btAssert( body.isStaticOrKinematicObject() );
+        //it could be a multibody link collider
         // all fixed bodies (inf mass) get mapped to a single solver id
         if ( m_fixedBodyId < 0 )
         {