vc-svn.el and "the underscore hack"

[AriT93]

This change may be trivial to others but as my elisp is not that
strong I though I would submit this.  On the windows platform
subversion can be configured to create it's directories as "_svn"
instead of the standard ".svn" I believe the reason for this was to
ensure it worked with websites served by IIS.  

This setting causes problems with vc-svn on windows.  vc-mode does not
recognize these files as being under version control.  To handle this
I have just replaced ".svn" with "_svn" in vc-svn.el.  So far I have
not seen any negative side effects of making this change.  However it
occured to me that there should be a more effective way of handling
this.  In looking at the file it would seem that eiter a variable
could be used to determine the name of the svn directory or an "or"
statement could be used where if no ".svn" directory is found a "_svn"
directory could be sought.

As I said my elisp skills are pretty weak but I am trying to get the
or statement to work. If I am able to get something working I will
submit a patch.

Ari
-- 

enjoy every sandwich

           -- W. Zevon