HP provisional termination

[AndresFerCervell]

This PR solves the first part of PR #1113. It includes the changes made in PR #1032, removing conflicts.

For every generic game, the Nash equilibrium selected by the Harsanyi Selten procedure is guaranteed (at least we haven´t found a counterexample).
Regarding non-generic ones, if an equilibrium is returned, there is no guarantee that it is the one we wanted (tracer result should be checked in order to be sure).
However, I haven´t found any example in the 477 games evaluated (random and the ones from the catalog or contrib) that happen to find an equilibrium after a tracer error. This means that the polishing method is not being used (if the tracer fails, so does it).

The games that always fail are, as I mentioned in our meeting, csg2.nfg, csg3.nfg and csg4.nfg and a random game of 2 players with 10 strategies each. This one is specially confusing because the Jacobian does not seem to be singular. The tracer gets a regret of 0.00542893, and the polishing method returns an all-zero profile in every position in spite of the safeguard I added. I will keep studying it.

We can say then that around 470/477 games get the expected equilibrium.

[AndresFerCervell]

The tests for this PR are failing on Python 3.10 with:
ERROR build_support/catalog/test_update.py - AttributeError: module 'pygambit.gambit' has no attribute 'Selector'
I guess it has something to do with the recent update of Gambit, but has no relation with my new code. Should I do something about it?

[AndresFerCervell]

Just understood the issue with the random game. When it approaches to 1, the first position of the tangent is almost 0 in the newton step. Therefore, t barely moves, and, when computing the next step size h, p_criterion(u, newT) - p_criterion(x, t) is zero.
We divide by that to get h, so it went to infinity. I have added a check that confirms the difference is greater than 1e-8.

The polishing method returned the all-zero profiles because the comparison between numbers and nan is false. Fixed that too.