This is really messy at the moment because I'm not sure whether the vim
team is interested, and I didn't want to put in the effort if it's just
going to be rejected, but I'm posting what I have here to start some
kind of discussion.

At the moment functions/other things need to be described, among other
issues. I have not yet tested to see if everything is still working with
vim, though I believe it works with neovim.

I'm also adding a patch file for vim-plugin.eclass, vim-doc.eclass and
vim-spell.eclass

I have a bug open on the bugtracker as well:
https://bugs.gentoo.org/612644

-- 
Aric Belsito