Updated ai code.
New Image to represent the computer player.
Moved implemention of a function header.
This in order for the compiler to make it inline.
Added underscore to public variables in the struct Input.
And changes to all files affected by this.
Added a cross image.
Will be used by when the user chooses non human or non computer players.
The player can now choose to play up against 4 ai opponents.
The ai is not implemented yet.