[WIP] nonlocal stability measure estimator

[Datseris]

This PR is by @andreasmorr and adds a nonlocal stability estimator construct that can compute every nonlocal stability measure at once during finding attractors and/or during the continuation.

[Datseris]

plotting is simple, we don't need a specialized function:

attractors_cont, all_measures = global_cont(stability_accumulator)

all_measures = vector ( dictonary ( measure_name => dictionary (id => number) ) )

mcs = [dicts["minimal_fatal_shock_magnitude"] for dicts in all_measures]

plot_continuation_curves(mcs, parameter_curve)

[Datseris]

I just found the paper: https://journals.aps.org/pre/abstract/10.1103/PhysRevE.93.042205 "Constrained basin stability for studying transient phenomena in dynamical systems".

It is identical to estimating the basin stability, but instead of weighting the distribution by a given density ρ, you weight the distribution by a "selector function". Only trajectories whose transients satisfy property "X" are counted. I think it is very straightforward to add this as yet another indicator in this PR.

We make a function indicator(u0, ds, tc) with ds the dynamical system. Inside this function the user may perform arbitrary numerics of whether the trajectory starting from u0, with arbitrary transient, satisfies the condition. tc is the convergence time that we have already estimated from the given initial condition at the previous step of the aglroithm of estimating all other stability measures. then the indicator function returns true/false, which tells whether to add u0 to the count or not.

@andreasmorr I can add this functionality in the code once the PR is ready to go.

[Datseris]

@andreasmorr have a look at my latest commit please. I've improved a bit the interface to use the existing call signature of global_continuation with AttractorSeedContinueMatch. No need to have a special method.

When using this in the project, just set the seeding keyword for ACAM. Don't make a new function that has a different default instead.

I've also removed the distance to bifurcation function as it does not fit at all the generallity of global_continuation. Moreover, there is no reason to assume only a single bifurcation occurs during the global continuation. In the examples I am using these methods, there are several global bifurcations happening.

Lastly, don't forget that this functionality needs tests before it is merged. Something needs to be added in the test folder. It also needs documentation: a simple example that is added in the Examples page of the documentation.