As described in T202, currently the maximum value of ASq (used for the accept/reject method of toy generation) for a given DP model has to be determined by trial and error and then set by hand.

This revision repurposes the LauFitter class to optimise ASq rather than a likelihood function:

ASqMax is found by minimising `-ASq` w.r.t. `m13Sq` and `m23Sq`.

This is done from multiple starting points: at cos(helicity) = -1, 0, 1 and m = m0 - Gamma0, m0, m0 + Gamma0

for each component in the model (resonant and nonresonant).

We intend to extend this to time-dependent models later.

This revision also takes the opportunity to perform some modernisation of some of the affected classes.