Smalltalk commit:

* Added UziProtocol, which will handle all communication with the Uzi firmware installed on the board.
* Changed UziInterpreter and UziProgrammer to use an instance of UziProtocol (instead of a SerialPort and an Arduino, respectively).
* Added UziSerialStream, a wrapper for the SerialPort that provides stream-like protocol.
Changed default pin mode to OUTPUT.
Added reporting of input pins. It doesn't seem to work well, though.