Share btGjkPairDetector, btGjkEpa2, btVoronoiSimplexSolver with SPU/Multithreaded implementation (remove duplicate code)

Make btTypedConstraint and btPersistentManifold both derive from btTypedObject to make SPU-side generic constraint solver easier.

Note: all build systems need to be updated: remove SpuVoronoiSimplexSolver.cpp, SpuGjkPairDetector.cpp, SpuEpaPenetrationDepthSolver.cpp, SpuGjkEpa2.cpp

src/BulletCollision/NarrowPhaseCollision/btGjkEpaPenetrationDepthSolver.h

@@ -25,6 +25,10 @@ class btGjkEpaPenetrationDepthSolver : public btConvexPenetrationDepthSolver
 {
 	public :
 
+		btGjkEpaPenetrationDepthSolver()
+		{
+		}
+
 		bool			calcPenDepth( btSimplexSolverInterface& simplexSolver,
 									  const btConvexShape* pConvexA, const btConvexShape* pConvexB,
 									  const btTransform& transformA, const btTransform& transformB,