Fix wonky controls
We do need to force videos to load, so seriously becomes "ready",
but not until after scripts are loaded
Forgot to add first person controls script
Trimmed mines video
Added some buttons to do some stuff
bug fix
bug fix: train chapter was not cleaning up after itself
Added Previous button
tweaked videos, volume
Reset accumulator when scene restarts
Audio voiceover for train chapter
keyboard control of chapter skip
Added voiceover audio files
Added music to 3D scene