USB-AO16-16A sample only supports unipolar calibration

[JHentges]

consider prompting user to set which board model is in use.
the -5U models must use DACSetBoardRange({some unipolar value})
the -10B (or -1B) models must use DACSetBoardRange({some bipolar value})
while the "standard" models need to use the appropriate value based on the user-set jumper-configured range