PicoBorg Reverse ARM mbed support

Hi,

I've created an mbed driver (which simply put is a C++ class wrapping the i2c calls) for the PicoBorgReverse; it was based on code from the Arduino library found on this forum.

It should be considered beta, for one thing it currently has no stepper support, but that would be straight forward to add.

It's been tested with the Nordic nRF51822 based BBC micro:bit riding a 4Borg, but it's not dependant on the micro:bit and should work with any mbed compatible board that has i2c support.

You can find the library here: https://developer.mbed.org/users/waynek/code/PicoBorgReverse/

Hope someone else finds it useful.

All the best
Wayne