Add roof monster groups

[LyleSY]

Creates two new monster groups to bring some life to roofs

Summary

SUMMARY: Content "Adds new monster groups 'GROUP_ROOF_ANIMAL' and 'GROUP_ROOF_ZOMBIE'"

Purpose of change

Makes roofs more alive and interesting

Describe the solution

Creates the two new groups, one for animals and one for zombies, fills them with animals and zombies that make sense on a roof exposed to the elements and places them on top of buildings instead of nothing at all or generic zombies.

Describe alternatives you've considered

Considered splitting this up or just doing one or the other but the general principles apply to both.

Testing

Spawned a bunch of animals on a roof, chased them off, then looked for bodies. No opposums in this version, everything else lived. Zombies on roofs have been heavily tested in tall buildings already like the hotel tower and mall.

Additional context

[curstwist]

you could add these spawns to roof_palette.json and get a lot of the individual roofs. It'll miss a small number of commercial buildings.

[Shodan14]

Now all me need are special roof zombies and maybe some that climb walls?

[LyleSY]

It looks like overmap spawn is the preferred way to do this. For now the zombie roofs aren't coded in a friendly way to do that, but I've moved all house roof spawns to use overmap. I'm still missing a lot of business roofs, but this is a big start. Moving to testing.

[LyleSY]

I'm still seeing build errors, but they all look like someone else's mess to me.

[LyleSY]

Testing looks good. I spotted a crow on a roof, I see new zombies on the office tower roof, the opossums don't jump to their deaths anymore, even when I beat them with chewing gum. I saw errors, but I think those have to do with the same build errors I'm seeing about SWAT zombies and mapgen.

[LyleSY]

Ah, the errors I was seeing were because I was using a test experimental with the eight edited files pasted in, which means they were a few days out of date vs. the rest. I think this is good to merge.