Activate 'Add to game' and 'Remove from game' buttons

Add action listeners so that the two 'add to game' and 'remove from game' are now active. They currently are only working on Strings to move them around, but the same logic can be applied later when using requirements from the requirement manager.

 Also changes some variable names for the new game tab panels and boxes to make it easier to look through and figure out what's going on.