Fungicide item enhancement.

Makes fungicide no longer 100% guaranteed to cure fungal infection, much less pleasant.
Adds rare anti-fungal medication that is 100% guaranteed to cure fungal infection, no side effects.
Makes basic fungicide more accessible.
Spawns, recipes, etc.

As mentioned here: https://github.com/CleverRaven/Cataclysm-DDA/pull/5789#issuecomment-33655763