Biome generator paints tiles, not vertices (1x1 "brush" instead of 2x2)

[Barhandar]

Wurm's digging is done on vertices. Painting tiles creates issues with all "resources" (tiles that give non-dirt items when dug), such as clay and tar. It needs an option to choose between painting tiles (for stuff such as adding packed dirt, taiga, steppe...) and painting vertices, or around vertices (resources).

Note that it needs to be option because sometimes 1x1 dirt is a terrible idea (e.g. if you want to cover mountains in small patches of dirt + trees).