Compact menu item hightlighting in the main_menu function
The main_menu function allows the player to select new game, load game, credits, and quit. When selected via the up and down arrow keys (or w and s) the selected item is highlighted. If the player presses enter, the highlighted option is activated. Currently, this section of the code is 20 lines long (lines 6 through 25), I believe it can be reduced by at least 10 lines.