Replace mode dumping designation

Another mining designation (in addition to: dumping, mining, leveling) that will replace existing material for resurfacing. e.g. if you have a large flat area at +4 covered in rock but you want it to instead be a surface of dirt you would use the replace designation at +3 and all the stone will be mined and then filled back up with whatever the dumping designation is in the mine control mining area is. Also excavators should also not excavate regions that are 100% of the dump designation material to stop them from getting stuck in mining/dumping loops.

I don't have any game dev experience, but I imagine this would be best implemented as giving the option to put a floor and/or ceiling on a control tower's area of influence; for example, a rock dumping control tower that only works up to level 3, and a dirt dumping control tower that only works above level 3.