Line length linter

[Commandcracker]

luacheck had lints for max line length, but selene not.

[Kampfkarren]

I'm okay with this as an optional lint, though you might want to consider Stylua.

[Commandcracker]

I didn't know Stylua exists :D I'll look into it. It would still be nice to have an optional line length linter, and it should be fairly easy to implement it, but I have 0 rust knowledge, so I won't be able to do it.