hand optimized paintScreen from memory buffer
hand optimized paintScreen from memory buffer

- SPI /4 SPI.transfer(): 3700 micros
- SPI /2 SPI.transfer(): 2670 micros
- SPI /2 hand-optimized loop (tight as it can get): 1170 micros

yyyc514/ArduboyLib,chcbaram/Arduboy,Arduboy/Arduboy,davidperrenoud/Arduboy,chcbaram/Arduboy,Arduboy/Arduboy,yyyc514/ArduboyLib,davidperrenoud/Arduboy