Add serduino, a module which allows serial communciation with arduino

This module allows a serial-connected Arduino to communicate with ScriptCraft.  It includes sc-serial.js, a serial port communications module; serduino.js, the serduino module that defines a serial protocol; and serduino.ino, an Arduino program that also speaks the serduino protocol.

More details are in the documentation in the code, but here's the Usage section:

	```javascript
	var serduino = require('serduino');
	// Create a connection object
	var conn = serduino.connect();
	// Start the connection
	conn.start();
	// After a second or two to make sure it's going...
	// Send an initial command to let the Arduino know we're here
	conn.writeDigital(2,0);

	// Now the Arduino will send us regular updates, and we can set pins
	
	// Put an LED and 1K resistor in series across pin 2.  Turn it on with:
	conn.writeDigital(2,255); // Any number other than 0 will work...

	// Or turn it on when any redstone is activated in the world...
	events.blockRedstone(function(event){conn.writeDigital(2,event.newCurrent);});
	
	// Put a potentiometer on analog pin 0 and read its value with:
	conn.readAnalog(0);
	
	// Callbacks can also be installed so a function is triggered when a pin changes...
	// This example launches some fireworks at location (-292,0,0) when pin 5 goes HIGH:
	conn.onPinChanged(5,function(pin,value) { 
			if (value) new Drone(-292,0,0,1,server.worlds.get(0)).firework();
		});
	// This example sets night/day according to an analog pin (eg. potentiometer, light meter):
	//  (It doesn't process 0's in case there's a flaky connection to the sensor)
	conn.onPinChanged(0,function(pin,value) { 
			if (value != 0) server.worlds.get(0).time = 6000+value*12000/256; 
		});
	```