06/02/2020: Fixes, Performance, Stability

Changelog for Supermedium: The VR Comic Book Reader (06/02/2020)

• Improve scrolling performance.
• Increase comic download speed.
• Improve UX of demo mode (e.g., indicate when a comic is not able to open due to demo mode).
• Fix uploaded comics sometimes not getting downloaded.

Next, we will:

• Add more indie comics.
• Explore reading comic files from SD card.
• Improve discoverability (and perhaps mapping) of page turn controls.