Another massive language reworking

with the ultimate goal of implementing keyword-argument semantics.
OpsArith tests passing again
More passing tests
GensData, GensChannel working
More tests for type mechanism
MaxType, RefType should work properly now

after some more in-depth testing.
More fixes
Retyping LibFist, part one
More retyping LibFist
First pass of typing done

I'll probably run into a couple of bugs in testing things out, though :)
Docs working again, starting to revive FistUI
FistUI working again

after deciding to keep the linear representation of HitAreas. Still need
to get variadic InputHitAreas working properly again.