NOP/clamping behaviour out of teh micro:bit runtime and into the glue layers of higher level
- Updates to many functions to provide explicut return codes.
- Updates to many functions to remove heuristic calidation (NOP/clamping/defaults)
- Updates to ErrorNo.h to provide clearer return values, and place return values in a better scope
- Updates to MicroBitDisplay to use enums where appropriate.