Added support for ellipse objects.
bugfix: Fixes drawing for when there are extra wide tiles are present.
Added support for drawing ellipse objects. The segments property of the object is used to determine how many segments it will be drawn with.
Changed the threshold for drawing small rectangles as larger ones from 20 pixels to 5 pixels. The undersized dimension will be overridden to 20 pixels.
bugfix: Tile objects were not correctly calculating the bounding box for orthogonal objects.
Tile objects now use the bottom edge to determine sort order. The property 'z' of the object (or the tile itself if not found) is used to adjust the sort order. 'z' is effectively how many pixels above the ground the tile object is.