Pin map definition cleanup.

serial.c

@@ -91,7 +91,7 @@ void serial_write(uint8_t data) {
 }
 
 // Data Register Empty Interrupt handler
-ISR(Serial_UDRE_vect)
+ISR(SERIAL_UDRE)
 {
   // Temporary tx_buffer_tail (to optimize for volatile)
   uint8_t tail = tx_buffer_tail;
@@ -140,7 +140,7 @@ uint8_t serial_read()
   }
 }
 
-ISR(Serial_RX_vect)
+ISR(SERIAL_RX)
 {
   uint8_t data = UDR0;
   uint8_t next_head;