Factor out TestListener from Devices unit tests.
Replaces printf from VisualTests.
Fix variable type in LabJackChecksums.
Cleans up LabJackScaffold.
-Splits up LabJackScaffold::configureLabJack on linux.
-LabJackScaffold on windows uses cleaner log message helper function.
- LabJackScaffold::Handle::create does not return a bool.
  The return value is never checked anyway.
Updates LabJackDevice documentation about DataGroups.
Simplifies LabJackScaffold logger use.
LabJack, fix cpplint warnings.
LabJackDeviceTest, use standard durations for input/output tests.
LabJackScaffold: moves code out of for-loop in handle creation.