Tileset size independence

[Alloyed]

The 16x16 restriction is a bit silly.
Possible problems:

• What should happen if the tileset and textset are different sizes?
• Is image size enough to determine character size? What about creaturesets?

[Dragoon209]

I would love for there to be varied tileset sizes, like the current implementation of TWBT in Dwarf Fortress. Basically, the 'Tileset' size determines the actual game window size, and a text tileset can be the same size, or smaller. non-square text can then be placed on the screen, which is more readable, and allows for the fitting of more text on the screen.

For an initial implementation, I think it makes sense to require that the image size be a multiple of the tile size (Tilesize X = Image X / 16, Tilesize Y = Image Y / 16). I'm not sure how creature image sets work, but I think they are similar. Hopefully somebody else can chime in with info.