remove Extras/obsolete/quickstep

improve serialization based on feedback: make it easier to serialize a single object, or single shape, or single bvh.
Modified Bullet/Demos/ConcaveDemo to use btSerializer to serialize the btOptimizedBvh (or optionally the trimesh+bvh)

You can also serialize trimesh without BVH, use:
serializer->setSerializationFlags(BT_SERIALIZE_NO_BVH);//	or BT_SERIALIZE_NO_TRIANGLEINFOMAP

Demos/OpenGL/DemoApplication.cpp

@@ -377,6 +377,7 @@ void DemoApplication::keyboardCallback(unsigned char key, int x, int y)
 		{
 			int maxSerializeBufferSize = 1024*1024*5;
 			btDefaultSerializer*	serializer = new btDefaultSerializer(maxSerializeBufferSize);
+			//serializer->setSerializationFlags(BT_SERIALIZE_NO_DUPLICATE_ASSERT);
 			m_dynamicsWorld->serialize(serializer);
 			FILE* f2 = fopen("testFile.bullet","wb");
 			fwrite(serializer->getBufferPointer(),serializer->getCurrentBufferSize(),1,f2);