share: pass named arguments

They are defined as named arguments and previous called as positional
arguments. As part of wrapping hg.share in an extension, I had to
extract arguments using some hacky techniques. Using named arguments
makes wrapping much simpler.

hgext/share.py

@@ -73,7 +73,8 b' def share(ui, source, dest=None, noupdat'
        the broken clone to reset it to a changeset that still exists.
     """
 
-    return hg.share(ui, source, dest, not noupdate, bookmarks)
+    return hg.share(ui, source, dest=dest, update=not noupdate,
+                    bookmarks=bookmarks)
 
 @command('unshare', [], '')
 def unshare(ui, repo):