(#859) Adding a few mini-bosses to the dungeon.

This PR adds two additional NPC mini-bosses to the dungeon, each with a certain gimmick.

There is a new Slime Host which uses a regular form, but has 'eaten' other psychos and have gained some of their power. It selects from a list of the available psychotic effects and spawns with two of them. It also spawns with items from a list which randomizes the rewards, as well. Each is to provide some form of variance for this mini-boss.

The next is an succubus plush and functions much like the angelic plush roaming the streets. It's "gift" was set to drop only one copy, symbolizing taking the plush itself and the 'spirit' possessing it.