Implementation of Inelegant Digging

Well, we've got to start somewhere. Digging is inside of this pull request, as well as the minor change that units owned get a small symbol over their head now to show that. I also ended up making a 'Beasts' folder, expecting that it is planned.

Looking forward to see how this all pans out.

While this digging implementation works when you have a single player, I expect it could become testy once you get quite a few players-- that will need to be looked into. I'll make issues for the specific issues which I can find once we have this merged. If we get it merged.