The ../../../pimoroni-pico path was selecting the "pimoroni-pico" directory adjacent my "micropython" directory
However I was attempting to build against one in a different parent directory.
This resulted in the MicroPython modules including the wrong (old) header and exploding.
The upstream MicroPython rp2 port has re-enabled -Werror so we need to either fix warnings or,
in the case of those generated by C++/C MicroPython binding weirdness, suppress them.
* fixed explorer library, added to cmake, and added quick demo
* display status of motors during demo
* increase motor power in demo
Co-authored-by: Jonathan Williamson <jon@pimoroni.com>