arduino-java
header:
	'R': next 10 characters will be the 10 digit rfid number passed as characters ('R' for RFID)

java-arduino
	'B'://command to tell arduino that a book is in stage B ('B' for Book)
	
	// needed in stage B: the (x,y) coordinates of the book in stage B
	'X': followed by the x coordinates of the book 3-digits ('X' for X-coordinate) 
	'Y': followed by the y coordinates of the book 3-digits ('Y' for Y-coordinate) 
	'L': followed by a 2-digit unsigned integer specifying the location the book (specified by 'A') needs to be sorted too ('L' for Location)