Code to run on O5 mother board (MB), to echo serial traffic to/from SPI bus,
for testing ModBus over SPI to the O5 daughter board (DB).

Build this and load it into the MB.  Connect the debug serial port of the MB
to a PC serial port.  Baud rate is 115200.  Connect the DB to the MB.
Now you can run ModBusView or ../../O5Expander/lib/test/oeTest.exe.


3/23/2016 - Tested with MPLabX v3.26, xc32 v1.40, Optimization level 1
