added acceptance test that beat ai; need to reevaluate ai strategy
cut over from string literal marks to use an enum; return Integer positions instead of strings; leave unselected position marks null
reorganize package structure to prepare for a new strategy that selects a position based on running every possible combination
reorganize tests to match main classes; rename strategy from rules to cumulative for clarity
move all tests to correct package
rearanging project to prepare for a new strategy for the ComputerPlayer
created PositionLocator that tries every combination of moves to identify the best possible move
created OpenPositionsLocator implementation to search for open positions on a board
created trial score calculator to calculate a score for each trial position within a row