Marloss infrastructure complete

This get the critters and spawns working, sets up the comestibles, and
includes the working fire-suppressor.  Thanks for the spotting, Kevin.
It's always the little things.

On balance fungal spawns are a bit rarer, but now there are three of
them, so total amount of fungus out to stay similar.

I'd like to get these merged sooner rather than later, but if you want a
few steps up the categories, I can work those out.