def fix_minus(self, s):
return s<EOL>
some classes may want to replace a hyphen for minus with the
proper unicode symbol as described `here
<http://sourceforge.net/tracker/index.php?func=detail&aid=1962574&group_id=80706&atid=560720>`_.
The default is to do nothing

Note, if you use this method, eg in :meth`format_data` or
call, you probably don't want to use it for
:meth:`format_data_short` since the toolbar uses this for
interative coord reporting and I doubt we can expect GUIs
across platforms will handle the unicode correctly.  So for
now the classes that override :meth:`fix_minus` should have an
explicit :meth:`format_data_short` method