Sorry I didn't remember why this was before, but I just ran into it testing the new wrappings for Angel4 -- we actually have to set the Vector and Color parameters to not be const so that the custom typemaps can kick in and generate them from Lua tables. 

I think I can make it so the typemaps kick in on consts too, so I'll poke at that a bit before merging this. But that explains why the const statements were initially taken out of the interface files. (Though of course they weren't taken out consistently, because, well.)