Ability to drag while the camera is moving.

Right now  when you drag a sprite, and the camera moves, the position gets messy.

For example, if your camera moves when you're near the edge, now you can do that while dragging a sprite.

However, a drag update still requires a mousemove, so there probably should be an update when the camera moves.. I didn't make this change yet as I'm not sure on the best approach.