I still had no time to test the lcd with the given code by myself. The diodes are just for lowering the voltage (each diode burns 0,7 V) since that LCD is usually powered with 3,3V. I don't know if it works with 5 volt, too. If so, it should also work without any resistors.
don't use the diodes... they're not reliable .. I think I burned one of those once using exactly that technique.use a proper 3.3v regulatorlike an lm3940 or something (good capacitor required with this part, read the datasheet)