This is a program that displays the discrete inputs and outputs defined by
the data structure declared within. Both the digital pins (Digital_0 and
Digital_1) are supported as either inputs or outputs. The ADC pin is also
supported but must be used as an input. All four sensor ports are
supported, or a subset of those.

The pins are displayed on the screen as follows:

   port_number.wire_color direction value

where:

   port_number is a single digit in the range 1 .. 4 corresponding to the
   sensor ports on the bottom of the NXT

   wire_color is a single letter representing the color of the wire
   corresponding to the pin. These values are 'W' for white, 'Y' for
   yellow, and 'B' for blue. (The black and red wires are always ground
   wires. The green wire always supplies power.) The white wire is the ADC
   pin, the yellow wire is the Digital_0 pin, and the blue wire is the
   Digital_1 pin.

   direction is a single character, either '>' designating an output pin,
   or '<' designating an input pin. The currently selected output pin is
   designated by '*' instead of '>' and it is that pin whose value will be
   changed by the toggle button.  Remember that no output pins need be
   specified, all could be inputs.

   value is '0' for Low and '1' for High

The cursor '*' can be moved amongst the output pins by use of the Left and
Right buttons. The value of the output pin designated by the cursor is
changed when the Middle button is pressed. If no output pins are defined by
the current mapping these buttons are ignored and no cursor movement or
value toggling occurs.

The program runs indefinitely and only exits when the Power button is
pressed continuously for a few seconds.
