Change player classes

Added ComputerPlayer interface, changed old ComputerPlayer class to LousyComputerPlayer, changed old SimplePlayer to HumanPlayer (now always type human). Names updates in all classes that used them, so could cause conflicts on other classes. Interface methods seem to must be public so getMove is now public, the interface also extends Player interface.
It looks like I killed the whole ComputerPlayer class but it is furthe down now called "LousyComputerPlayer", its gits fault due to the new interface and the old class being named the same.