more memory leak fixes in demo and btSimpleBroadphase.

- deleting object (END key) needs to release
- call destructor of pair cache

src/BulletCollision/BroadphaseCollision/btSimpleBroadphase.cpp

@@ -77,6 +77,7 @@ btSimpleBroadphase::~btSimpleBroadphase()
 
 	if (m_ownsPairCache)
 	{
+		m_pairCache->~btOverlappingPairCache();
 		btAlignedFree(m_pairCache);
 	}
 }

src/BulletCollision/BroadphaseCollision/btSimpleBroadphase.h

@@ -77,7 +77,7 @@ protected:
 	void freeHandle(btSimpleBroadphaseProxy* proxy)
 	{
 		int handle = int(proxy-m_pHandles);
-		btAssert(handle > 0 && handle < m_maxHandles);
+		btAssert(handle >= 0 && handle < m_maxHandles);
 
 		proxy->SetNextFree(m_firstFreeHandle);
 		m_firstFreeHandle = handle;