There is some error in BlackJack.py and fixed it.

Fixed Points
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+ an ace should be determined to be 1 or 11 only after all cards are investigated

+ dealer can also be busted, add an judgement on whether dealer has busted

+ there is an error in counting player&dealers wins and looses, which alfter press deal button, counter is added twice

+ flag1 has no use, delete it

+ deal has an error that at first each person has two cards. That is, count should be init as 2 instead of 0

+ add an maximum of 5 on dealer's hand. When dealer has five cards, force dealer to stand