Continue menu music through window changes

[aberlanga]

Currently in the main menu if you open any of the other windows, instructions or highscore, the music will reset upon closing the highscore or instruction window. Main Menu music should be maintained until a play game window starts. This is because the window closed function is overridden. A function that checks whether the music is still playing and accounts for this should fix it.

[xavierholt]

F17 OK: 100 XP

[brianslee]

W18 Ok 100 Points

[brianslee]

Fixed Closed W18