[0.13.x] Ghost placement priority

[BlackKnight]

I think this is a bug - although not exactly a critical one. Placing an initial ghost maintains a priority over later ghosts that might overwrite the same tiles.

This is most easily demonstrable through floor tiles.
1. Starting setup
2. New floor tiles are ghost-placed. Though there are not enough to completed the request so some are left as ghosts awaiting placement.
3. All tiles in step 2 are overwritten with concrete tiles via ghost placement. This suddenly makes the tiles missing from step2 available in the inventory and overwrites all just-requested concrete tiles which intersect.
4. End result.

Expected result, the most recently placed ghost-placement on that tile should take priority... (although it can result in some unique random pixelated art)

[Rseding91]

That's just how ghost building works.

Remove the existing ones first if you don't want them to do that.