Add music and sounds

[subscorp]

Add a menu with the following options:

• On/Off options for both music and sound effects.
• Allow the user to control the volume of both music and sound effects.
• Allow the user to choose from a selection of options.
• Disable selection and volume control for music/sound effects if it's irrelevant.

Also, need to be done:

• Handle credit to creators.
• Test cases.