Local optimisers in ask-and-tell as a step up towards hybrid optimisers

[MichaelClerx]

There's a few tickets (#54 #55) about adding more traditional, local optimisers to Pints, by wrapping around e.g. SciPy.

Some ideas:

• Nelder-Mead
• Levenberg-Marquardt Add Levenberg-Marquardt optimiser (requires sensitivities) #934

However, if we were to write some of these methods (Nelder Mead, Powell's methods, Brent's methods) in ask-and-tell form, it would open up a door to hybrid optimisation methods, e.g. an XNES variant with an internal Nelder-Mead

See e.g. https://www.frontiersin.org/articles/10.3389/fbioe.2015.00209/full

It would be great to get a student who is interested in optimisation to have a look at adding the traditional methods

[MichaelClerx]

Update: we have Nelder-Mead now

[MichaelClerx]

Closing this, as both parts have a ticket of their own