Fix memory leak due to batchRayCast never deleting the btTaskScheduler.

(and issue with TaskScheduler/btTaskScheduler.cpp, add JobQueue::exit, call it first, since it uses the m_threadSupport which was deleted before the destrucor was called.
Use a hashmap to store user timers, to avoid allocating many identical strings.

examples/SharedMemory/PhysicsLoopBack.h

@@ -93,6 +93,9 @@ public:
     virtual int getCachedUserDataId(int bodyUniqueId, int linkIndex, const char *key) const;
     virtual int getNumUserData(int bodyUniqueId, int linkIndex) const;
     virtual void getUserDataInfo(int bodyUniqueId, int linkIndex, int userDataIndex, const char **keyOut, int *userDataIdOut) const;
+	
+	virtual void pushProfileTiming(const char* timingName);
+	virtual void popProfileTiming();
 };
 
 #endif //PHYSICS_LOOP_BACK_H