WINTERMUTE: Cleanup
Merge branch 'wme_lineartickets' into wme_rendering

This replaces the (quadratic time) renderqueue drawnum logic by a
(linear time) approach based on following along the queue with an iterator.

This branch first implements the new iterator logic next to the old drawnum
logic, adding asserts that they produce identical results to facilitate testing
and debugging. The old code is removed after that.
WINTERMUTE: Add displayTiled function to replace repeatLastDraw

This avoids queueing many tickets for a UITiledImage, replacing
them by a single tiled ticket.