changed to even parity in demo main function.

src/avr_usart.c

@@ -25,9 +25,8 @@ int main() {
 
     init_usart0(); 
 
-    //enable parity, because the internal 
-    //crystal is garbage
-    serial0_enable_parity_bit(2);
+    //enable even parity
+    serial0_enable_parity_bit(1);
 
     //enable interrupts
     sei();