[PATCH 0/3] Updates to git-add--interactive

Based on feedback from Junio last night here is a new series. This one goes on top of the "next" branch.

I moved the pathspec validity checking into builtin-add, thus simplifying things considerably. I also enforced some strict assumptions about how the optional arguments will be passed from builtin-add to git-add--interactive; I can do this because it is the only caller, and it once again makes things a bit simpler.

I don't expect this to actually be applied as-is, as there are some doubts I have which I have added to the emails for each patch. In particular there is a performance issue with the pathspec validity checking (no idea why it is so much slower than just invoking git-ls-files), and the behaviour is not exactly where I'd like it to be (things like "git-add -i ." don't work because "." is considered invalid).

So looking for feedback on how to address this issues and will resubmit.