Collapsed multi-tab settings into 1, since there weren't that many

• Added Particle Density setting
• Added Windowed mode setting
• Game defaults to Fullscreen
• Added option to hide Moves Available label
• Hid Seed label since it isn't useful to players
• Removed unimplemented Custom Game button
• Removed "Quick Play" labels, since that's the only type of play
• Added Credits dialog with new music