Sprite.abs_x, abs_y, abs_pos, etc.

[acbart]

Currently, there is no way to conveniently refer to sprite's coordinates in a global sense - applying any transformations from the parent views. That is, if you say Sprite.x, and that Sprite has a parent View with an offset, you have to manually calculate the absolute position on the screen.

Currently, we have a mechanism for handling this: collide_sprite/point/rect all use the internal _warp_collision_box method to correctly calculate absolute position. We just need new properties on sprites and views to easily get (but probably not set) the absolute position as calculated by the _warp_collision_box function.

This is also necessary for Views.