Add filled resizable background for clicker game. All changes in "Cookie" sprite. Don't play in the editor, far too slow, play on the project page. Only the bottom left corner of the window can be dragged so far. Don't drag the corner past the right one or the top one, or else the filling algorithm breaks.
All by me, except for the idea of the rectangle filling algorithm. The implementation of the rectangle filling algorithm is unique to me though.
