fix over-estimated seven pair win rate

[Ledenel]

For now, a hand with drawn tiles will be considered as win:

1. IFF the union of the hand and drawings contains at least a win pattern.

But for seven pair win pattern, it will over-estimated much more than normal type wining. Infering from 1), the model will assume that all tiles which will form a pair will be choosen to keep in hand, but it is really hard (nearly impossible) to predict which tile will eventually form a pair (it seems all the same). The prediction from player is not statically significant different from random guessing.

For comparasion, 23s has nearly 2 times chances than 13s to form a meld, so choosing is quite easy.

(i.e. 1155m123345p5566s, 6 draws, it will consider to discard 1/5p to expect seven-pair wining, which is not acceptable by most of the players.)

[Ledenel]

Since 7-pair wait state is very simple, Markov chain can be used to modeling random selecting instead of running Monet Carlo simulation.