In roborio GCC 5.5, __FRC_ROBORIO__ has been added directly to the
compiler. So we can instead use that to detect if we are build for the
roborio, and in a much more reliable way.
* Modify halsim to be able to load extension libraries if they are available.
It will read the list of libraries to try from the HALSIM_EXTENSIONS
environment variable. Multiple libraries can be given if separated
by ';' (Windows) or ':' (Unix).
The library must have an 'HALSIM_InitExtension' method that returns >= 0 on success.
The library is expected to use the interface expressed by
hal/src/src/main/native/include/MockData
* Add a simple halsim library that just prints robot values.
This makes a good test bed for cross platform purposes,
and provides the ultimate in light weight simulators.
This initial version only prints PWM values.
