Add xmega compiler while default avr compiler does not support xmega
Add xmega compiler while default avr compiler does not support xmega

jaehong/Xmegaduino,jaehong/Xmegaduino,jaehong/Xmegaduino,jaehong/Xmegaduino,jaehong/Xmegaduino,jaehong/Xmegaduino,jaehong/Xmegaduino