Mission Expansion WIP

I'm doing a bit of fleshing out of missions to eventually add a reason to explore new buildings.

Demon Slayer 1 (in game) - Kill a Jabberwock, a monster slightly more dangerous than a hulk 
Demon Slayer 2 (in this update)- Kill 100 Zombies, help the other survivors out
Demon Slayer 3 (on its way)- Kill the Horde Master, a master zombie has taken residence in a local building and you must kill the Master... beware the group that surrounds him