Simultaneous Updates

[WhiffleFish]

For simultaneous updates we currently traverse the tree separately for each player to accumulate regrets.

However, we can actually just update both players' regrets AND match regrets in a single tree traversal.

CounterfactualRegret.jl/src/solvers/CFR.jl

Lines 174 to 181 in 6be7725

	for t in 1:N
	for i in 1:players(solver.game)
	CFR(solver, ih, i, t)
	end
	regret_match!(solver)
	cb()
	next!(prog)
	end

For reference:
https://github.com/maichmueller/cfrainbow/blob/1d4ecefc87f1566770b5b358303c5eee1aa97227/src/cfrainbow/cfr/cfr_vanilla.py#L28-L57