UltraNest support

[JohannesBuchner]

Would you be interested to add support for https://johannesbuchner.github.io/UltraNest/ ?
The interface should be very similar to dynesty.
UltraNest is a very reliable tuning-parameter-free algorithm. It can be faster than dynesty, especially if you take advantage of vectorization.
It also supports resuming from disk and MPI parallelisation, if that is useful to you.

[arm61]

Hey @JohannesBuchner, I had it on my radar to implement UltraNest support (it is in my OmniFocus list). I wanted to wait for the JOSS review to complete.

[arm61]

I will keep this issue open as a reminder for myself.

[arm61]

At the same time, should consider including zeus (https://zeus-mcmc.readthedocs.io/en/latest/)