Add IsStrictNash, IsBestResponse to pure strategy profiles

[tturocy]

From commit db49a3 (and release 14.0.2) the PureStrategyProfile class has a member function IsNash(), which determines if the profile is a Nash equilibrium of the game.

To this, a few other similar and useful functions can be written:

• IsStrictNash(): returns True only if the profile is a strict Nash equilibrium (that is, the payoff is strictly greater than any deviation payoff)
• IsBestResponse(GamePlayer): returns True if the player is playing a best response
• GetBestResponse(GamePlayer): returns a list of strategies which are best responses for the player (including possibly the strategy the player is playing, if it is a best response).

[neo9988]

Hello, Can I help solve this issue?

[tturocy]

Yes.