This PR greatly simplifies the loading bar. For now, the loading bar can only be started or stopped.

By default, starting the loading bar:

1. Starts loading bar at 7% width
2. Gradually increase the progress bar every 1 fps (via requestAnimationFrame)
3. Progress bar stops at 64% (this requires 323 frames, or around 5-6s on a 60 fps screen)

Stopping the loading bar:

1. Sets progress bar width to 100%
2. Wait for 200ms
3. Begin reducing opacity by 1% every 1 fps (via requestAnimationFrame) which requires roughly 100 frames, or ~1.5s at 60 fps

TODO:

• add example page to display full load
• add param to configure load speed
• add param to manually configure loading bar progress