Allow larger tile size in Map editor

I'm finding the limit of 64x64 for tile size in the Map editor to be too small for my game--I'm using vector graphics, and so when I render them at only 64x64, they lose quite a bit of sharpness and don't look very good.

In my opinion, the limit should be at least 256x256 or maybe even higher. It may not be practical to support a high enough resolution for tiles drawn at a very large scale, but supporting at least 256x256 would enable tiles to be drawn at size '20' and look pretty good.