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

src/BulletCollision/CollisionShapes/btCollisionShape.cpp

@@ -109,3 +109,10 @@ const char*	btCollisionShape::serialize(void* dataBuffer, btSerializer* serializ
 	return "btCollisionShapeData";
 }
 
+void	btCollisionShape::serializeSingleShape(btSerializer* serializer) const
+{
+	int len = calculateSerializeBufferSize();
+	btChunk* chunk = serializer->allocate(len,1);
+	const char* structType = serialize(chunk->m_oldPtr, serializer);
+	serializer->finalizeChunk(chunk,structType,BT_SHAPE_CODE,(void*)this);
+}