Added LCD, improved dynamic arduino power control

Added the LCD and set up the LiquidCrystal class from the arduino
library.  Arduino now prints out play, stop, and pause when it receives
these 3 commands, and also displays two different errors if they occur.

I added a button to the main dialog to cycle power on the arduino.

I also replaced the 9v battery that used to power the dynamic arduino
power control with a 9v power supply, and so far it seems much more
stable.