Added comments to example.

Updated constructors so that debug enabled is called in youngest child.  This prevents calling functions that use values defined in child header.

Updated UART write to support up to 4 channels.

Udpated debugging to select uart channel based on DEBUG_ENABLED value (0 = disabled, 1 = UART 1, 2 = UART2, 3 = UART3).  Debug uses LINX UART functions.