- rebalanced the campaign and survival levels

- added the concept of a swarm (multiple ghosts of the same type clumped together)

- regular enemy version of Casper and Mr. Stay Puft

- depth of ghosts changes based on the orientation

- updated some assets

- fixed some issues with campaign levels 4 and 5

- fixed a bug with the repair button showing/hiding when not supposed to

- added foliage to campaign levels