Avoiding conflicts in .hgtags

[Greg Ward]

On 08 December 2008, Peter Arrenbrecht said:
> I think Mercurial should have a specialized merger for such files.
> There are others, like .hgsigs, and there will be more, like
> .hgsubrepo, etc.

The same thought occurred to me, so I've started writing a very
simplistic and naive script to merge .hgtags files.  Will share it
here for feedback when I've got it working.

       Greg