Add DragonFly optimizer Example

[eslam69]

This is a minimal example that demonstrates the flexibility of brian2modelfitting specially in working with different back-end optimization libraries.

• This example is compatible with the latest version of brian2modelfitting at the master branch on GitHub.
• I used Dragonfly library which offers Bayesian optimization and some evolutionary algorithms.

[eslam69]

I encountered this issue #41 during the development of this example.

[mstimberg]

Thanks for the contribution and apologies for taking so long to reply. This looks very good as it is, I wasn't aware of the DragonFly library! The only downside I am seeing is that the example model that you used is a very "boring" one, it would be nice to show one where we can have actual traces that look like a "real neuron". Would you mind e.g. changing it to the one used in https://brian2modelfitting.readthedocs.io/en/stable/examples/hh_multirun.html (no need for the second run, of course)? It could be any other model, but I'd find it much more appealing to have a plot in the end instead of printing out the results. Thanks again!

[eslam69]

Thanks for your feedback and suggestions.

[mstimberg]

Thanks also for the changes here – same comment as for your other PR: all looks good to me from a quick review, but the merge has to wait for a more detailed review in about two weeks (don't worry about this being after the GSoC application deadline).