Better pre-written signs, prefix, mini-Zs option

* Pre-written signs were improved. This includes:
- %c% for lootchest signs is replaced with the first chest's y coord
found
- A description is added to the item that's created
- You should be able to use them in Survival now, too
* The prefix can be modified for everything in the front-end
* The mini-zombies can be deactivated if you don't want them