help wanted for vc-hg.el

[Dan Nicolaescu <dann@ics.uci.edu>]

vc-hg.el has been checked in recently. Unfortunately Ivan Kanis, the
vc-hg.el author does not have much time to maintain it. 

I implemented some of the missing functionality, but there are some
things that still need to be done. Here's a tentative list:

- thoroughly test and fix problems that are found

- write regexps for log-view to understand the "hg log" output

- implement vc-dired
- implement vc-snapshot 
    I have never used the 2 above, so I don't know much about them, or
    even if they make sense for Mercurial. 

- Implement Stefan Monnier's advice: 
    vc-hg-registered and vc-hg-state
    Both of those functions should be super extra careful to fail gracefully in
    unexpected circumstances.  The most important such case is when the `hg'
    executable is not available.  The reason this is important is that any error
    there will prevent the user from even looking at the file :-(
    Ideally, just like in vc-arch and vc-cvs, checking that the file is under
    mercurial's control and extracting the current revision should be done
    without even using `hg' (this way even if you don't have `hg' installed,
    Emacs is able to tell you this file is under mercurial's control).

Help would be greatly appreciated.

Thanks

        --dan