VSS, UI updates

The head revision now show progress better, though probably far too
infrequently for large projects (a 1 to 20 scale is too crude when
taking hours to submit tens of thousands of files, but it's better
than nothing).

I can parse all of the (single) real world VSS repository I have (thanks
Robert!), but I haven't pushed it in to Perforce yet.  I've been
using the null destination (Dest:  null:) to test just the parsing
as it's lots faster.

The user interface's editing feature is more stable and usable.

- Barrie