Add upside-down printing

[doublevie]

Hello . i work with the upside down printing mode . Finally i found it in the epson escpos ref and it work for me
$printer -> getPrintConnector() -> write(PRINTER::ESC . "{" . chr(1));

WORKS ON GPRINTER WIFI PRINTER

[mike42]

Cheers, thanks. I've made sure it works on my own printer and submitted a change to implement this.