Modified to compile under OS X. Added reset functionality

Hi, and thanks for a great boot loader.

I've modified raspbootcom.cc to reset the rpi when it receives a SIGUSR1 signal. This is done by toggling the DTR line on the serial line high, then low. A standard NPN transistor is needed on the rpis P6.

I'm sure there's room for improvement, as I'm just beginning to understand all this. 

I've also modified the source to cleanly compile on OS X. 

Sending you this in case you're interested.