Improving subversion support.

[Wilfred]

This ensures that .svn directories are ignored, and we use subversion's
list command to get files for performance.

[bbatsov]

Looks good. The .svn dirs were ignored recursively, right? I wonder why I haven't include .svn and CVS here originally. Perhaps this was for only a top-level check back then.

[Wilfred]

Yep, they're ignored recursively. Are you happy with this PR? I'm happy to make changes if not.

[Wilfred]

Thanks! :)

[bbatsov]

No, it's fine as it is. Thanks!

Hopefully someday subversion projects will be recognized automatically, but I don't use svn anymore and I don't have time to implement that.

[Wilfred]

I've actually got an implementation of subversion project root detection: Wilfred/repo-root.el@70ca866 . Happy to send another PR.

By the way, would there be any interest in separating out the 'detect the root of this repo' code as a separate package? I have several packages that would really find the functionality useful, but I'm reluctant to pull in all of projectile as a dependency.

[bbatsov]

Sure, I'd take a PR for this. Didn't know it was implemented in vc.el.

As for the separate package - I've considered this myself (since I've needed similar code elsewhere), but I haven't gotten to actually doing it.