This fix lock-ups on UART errors (for example when disconnecting
and reconnecting RX/TX wires or if the method Serial.begin is
called while another device is already transmitting).

Fixes #4

It seems that

   #include <stdint.h>

is able to undef "min" and "max" previously defined. With this
commit we make sure that they are defined as last.

Fix #10

This allows to burn bootloader with Sam-ICE too.

http://forum.arduino.cc/index.php?topic=330699.0

Fixes #7

as in the other Arduino cores