Write or overwrite a `Survey` to the specified .DAT file

def write(self, outfname=None):
        """Write or overwrite a `Survey` to the specified .DAT file"""
        outfname = outfname or self.filename
        with codecs.open(outfname, 'wb', 'windows-1252') as outf:
            for survey in self.surveys:
                outf.write('\r\n'.join(survey._serialize()))
                outf.write('\r\n'+'\f'+'\r\n')  # ASCII "form feed" ^L
            outf.write('\x1A')