Working harmonisation and arithmetic + tests + caching

Created by: DreamingRaven

More complex arithmetic operations are now possible, with automatic harmonization of parameters and scale. Some intelligence to it should be added in future to not harmonize in cases where scales are massively incorrect.

Reverse arithmetic as well as forward arithmetic with mul add rmul radd are now working. Along with their tests, with minor noise inaccuracies.

Caching has also been implemented to reduce the time to compute, without having to re-compute unserialisable objects.