Remove LiquidCrystal library, Add display to LCD functionality.

- Removed All references to LiquidCrystal library. According to the
datasheet he gave us, the particular board we're using only uses one
pin for serial communication, so that LiquidCrystal library won't be
useful to us.

setup() now starts serial comms with LCD and prints "Volts!" on the
second line.

loop() has been modified to 1) select the first line of the LCD
display, 2) print the latest value of digitalVoltage, 3) delay 100 ms.

selectLineOne() and selectLineTwo() have been modified to comply with
Arduino 1.0, which deprecated and removed the BYTE constant. Now the
Serial.write() function is used, which automatically sets the length of
communication to one byte.