Pave Mined tiles

[ImpalerWrG]

Currently when you mine out a tile it has that dark grey color which distinguishes it from natural cave floor, but we are unable to pave this type of tile which is kind of visually jarring and ugly when alongside the cleanly paved areas that were original natural cave floor. and it would be more consistent if everything could be paved. I hope the code that manages cave-in is not tied to the tiles visual appearance (that would be really sloppy design). While their might be some risk of people forgetting ware the safe places to mine are that's their own fault.