IBP banding data system: Internal maintenance specification

For display of a Species object within error messages. We don't display the .spNo field because it is not currently used anywhere.

# - - -   S p e c i e s . _ _ s t r _ _   - - -

    def __str__(self):
        '''Return a string representation of self.
        '''
        return("%s [%s/%s]" %
                 (self.eng, self.spec4, self.spec6))