Optimize return value of util._matcher for hgignore case

Optimize return value of util._matcher for common command line case This will trigger every time somebody runs something like "hg diff" or "hg status" without any arguments. The important part here is returning util.always as the match function, which is a much simpler (and faster) function than the usual return value, and allows other code to just skip the filtering if it knows all files will match.

remove unused "head" hack from util._matcher

locate: exit(1) if we didn't print any file

change locate to use relglobs by default This makes its default behaviour useful again (issue108), and changes it search the entire repository by default (instead of just the cwd), just like all other commands. It also hides issue204 by default, but you'll still see the same behaviour if you give it a relpath: pattern.

localrepo.walk: if we're walking a specific revision, sort the files This is more consistent with our behaviour while walking the working directory.

dirstate.statwalk: explicitly test for ignored directories This removes a hack where we appended '/' to a dirname so that: - it would not appear on the "dc" dict - it would always be matched by the match function This was a contorted way of checking if the directory was matched by some hgignore pattern, and it would still fail with some uses of --include/--exclude patterns. Things would still work fine if we removed the check altogether and just appended things to "work" directly, but then we would end up walking ignored directories too, which could be quite a bit of work. This allows further simplification of the match function returned by util._matcher, and fixes walking the working directory with a --include pattern that matches only the end of a name.