Fix butchering

[amylizzle]

About the PR

A minor oversight meant all critters could be butchered, even when butcherable was FALSE.

Also I fixed a tiny runtime I found on sawflys with no AI

Also capybara butchering is now considered monstrous.

Changelog

(u)Amylizzle
(+)Some critters were butcherable when they shouldn't have been. If you find a critter that isn't butcherable but should be, report it as a bug.

[NightmareChamillian]

Ideally, I'd like sawflies to be butcherable for the sake of the poor janitors, just that they don't yield.... flesh. If you want, you can just drop the change for sawflies and I'll cook something up to fix it later today.

[amylizzle]

It isn't specifically doing anything to sawflies, it just makes it respect butcherable. If you want sawflies to be butcherable, but produce something not meaty, you could add butcherable = TRUE to the sawfly mob and set meat_type to something sensible.