Change arguments to game_means_count and level_means_count and create
adjusted_means.m

- adjusted_means.m adjusts the game means by the level means and outputs
  adj_means.mat.
- game_means_count.m and level_means_count.m change to maximum
  threshold. Output files gl_mean_level.mat and gl_mean_game.mat change
  because of this.
- add gl_key.mat because extracting which game in output matrices may
  become important in future when creating graphs, summary stats, etc.