Improve "OSA UCS" to "CIE XYZ" conversion.

[KelSolaar]

Our optimization process does not do a good job with dark colours and actually fails miserably, we should revise our approach:

References

• https://www.osapublishing.org/josaa/abstract.cfm?uri=josaa-30-8-1508
• https://colab.research.google.com/drive/1PQWMv61b1Kc0XRX9NX-u3YU60uB94I6R#scrollTo=9hlRuWm5iXew&uniqifier=2
• https://arxiv.org/pdf/1911.08323.pdf

[KelSolaar]

I gave a stab at a Newton-Raphson minimizer as described by Moroney (2003): https://github.com/colour-science/colour/blob/feature/osa_ucs/colour/algebra/optimize.py

Good thing is that it is vectorised, so it is super fast! Problem is that it does also fail for dark colours: