Write this catalog out to a text file.

def to_text(self, filename=None, overwrite=True):
        '''
        Write this catalog out to a text file.
        '''

        table = self.standardized
        #table = hstack([self.identifiers,
        #                self._coordinate_table(),
        #                self.magnitudes,
        #                self.errors])

        if filename == None:
            filename = '{}.txt'.format(self.name)
        self.speak('saving to {}'.format(filename))
        table.write(filename, format='ascii.ecsv', overwrite=overwrite)