Oh Yeah! Also be persistent about Megaboss selection

- The K00-LAYD was exploding so hard it made the game detonate. OOOHH YEEAAHH!
- Choose a Megaboss once instead of trying to spawn all of them, so we can't
  gimp the selection by Transporting away and back again to get different ones
  each time.
Merge branch 'master' of https://github.com/Kyle873/DoomRPG