Choice of VCS in multiple imports from manifest file
After #405 (closed), we'll be faced with the fact that the multiple imports feature is Mercurial-centric in Heptapod, and of course, we'd like to import Git repositories as well.
Either we'll have to let the user specify it, or we'll start if possible with a simple detection phase. Given that repositories to import are given by URLs, it's rather easy to check if they are Git or Mercurial. How to include that in the creation flow is where the difficulty can be.