incorporated utility function into AI strategy.
added weights for center
tweaking utility function weights, minor bug fixes
also took away surrounders weight to verticals on last commit
not sure what the changes are here
tried to add weights for surrounders function, but there's a bug
brought no-gos and go-s over to the board class to replace use of
stacks in utility estimator with gos and no-gos
made a new function that gives all possible fours in a row
that will hopefully replace surrounders heuristic (much better)
and de-bugged it well
added function for num of lowest open threes
took away print statements, added simpler utility functions to strategies module
added center weight to utility estimator, and added to do note by
utility estimator function
added pruning function for fours above open threes, only for opponent, and changed the total possible fours to return the list instead of its length
modified pruning function to also prune availalbe fours an even number above own open threes
fixed bugs and changed play functions to reflect new simpler utility functions
changed no_gos function for odd even indexing
addded cutoff parameter in basic_strat function so it can be
cutoff at different levels of the tree
added defaultdict to keep track of moves in certain columns in board class
controlling open threes function
no_gos function needs two definitions for the two different players, first and second. fixed little bugs
modified strats function to reflect two player fork in no_gos_function
changed key utility function to an end_state utility estimator, and
added weight to it, included it in strategy function
and fixed couple of bugs
added cutoff to strat_basic to include extra parameter of where basic strategy feeds
list to other strategy