Add sound playback

[humdingerb]

Implement playing back sounds for:

• when starting a new game
• moving a tiles
• merging tiles
• no more moves
• reached 2048
• reached new highscore (only play once)

The actual sounds used can be researched later.
Load sounds with FindPaths(B_FIND_PATH_DATA_DIRECTORY). That way users could override the packaged sounds.

Add an icon button to turn audio on/off.