checkered terrain auto tile

[city41]

Checkered terrain is so tedious to use. Add a Checkered Terrain - Auto entity that does auto tiling. Keep all the other checkered tiles around to give full control to those who want it. Also advertise the auto one, perhaps in the item chooser highlight it in some way and let people know it's probably what they want to use for checkered.

Could probably auto tile grass too, using the same system.