Implement a calibration algorithm

[disassembledd]

Hi! I'm quite new to the embedded scene and, following the embedded wg's book, recently became interested in the micro:bit. The book references a wonderful BSP for it, however, it lacks many of the APIs that the official C++ lib offers. I noticed this crate is often used to alleviate that, however, I don't notice a calibration function currently implemented.

My proposal would be to implement the algorithm currently in use in the micro:bit API which, in turn, is implementing the manufacturer's algorithm. I am far from decent enough at Rust or familiar enough with embedded programming yet to do so myself, unfortunately.