Implement Powell's method

[nick-maslov]

It would be great to have the Powell algorithm like in scipy optimize: https://docs.scipy.org/doc/scipy/reference/optimize.minimize-powell.html#optimize-minimize-powell

[stefan-k]

Thanks for opening this issue! This would be an ideal initial project for someone interested in contributing. I would of course provide mentoring/support if needed.

[Trombach]

Hi @stefan-k, came across this library and would love to contribute. I'll have a look at this when I have a bit of time to spare.

[stefan-k]

Great! :) Feel free to open a PR when you're ready or when there is something to discuss.