a few modifications to BulletMultiThreaded, add 'setNumTasks' to interface, reorganize DMA transfers to allow larger btBroadphaseProxy size

src/BulletMultiThreaded/btThreadSupportInterface.h

@@ -37,6 +37,10 @@ public:
 
 ///tell the task scheduler we are done with the SPU tasks
 	virtual	void stopSPU()=0;
+
+	///tell the task scheduler to use no more than numTasks tasks
+	virtual void	setNumTasks(int numTasks)=0;
+
 };
 
 #endif //THREAD_SUPPORT_INTERFACE_H