vcsdiff: async mode?

[blueyed]

It would be nice if vcsdiff's system call could use Vim/Neovim's jobs by default, i.e. it would call the git-diff command and update the signs on exit.
This likely needs some refactoring, but should make the experience better, especially with larger files/repos.

What do you think?
(FWIW https://github.com/airblade/vim-gitgutter supports this)

[tomtom]

I don't know neovim. I think it should be doable with vim8's api. The new quickfix-related additions could also come handy too. I personally don't have the time though for implementing this feature. If you're interested, I can grant you write permissions to the repo. I'd also be happy to accept some pull requests.