ALVR v20.2.0

Changes

• Add Flatpak build (by @CharlieQLe #1683 #1724 #1735 #1742, @Meister1593 #1769)
• Finish VRCFaceTracking support (by @zarik5)
  • You can download the ALVR Module from the VRCFaceTracking app itself.
  • Only supports the Quest Pro at the moment.
• New more performant sockets implementation (by @zarik5)
  • Zero copy + zero allocations, and provides better packet prioritization.
• Avoid controller freezing during high latency (by @zarik5)
• Add message popups on Linux (disabled on the appimage build) (by @zarik5 #1711)
• Show backtrace on unhandled exceptions (Windows only) (by @zarik5)
  • Previously these would make SteamVR hard crash without any useful log
• Optionally show full backtraces for logs (by @zarik5)
• Add option to select client log level (by zarik5)
• Make Log tab stick to bottom (by @zarik5)
• Encoder fixes on Linux (by @nowrep #1751 #1753 #1767 #1768 #1796, @Vixea #1805)
• Use Constant bitrate mode by default
• Support rolling video recording (by @zarik5)
• Fix OpenGL crash on the client (by @ShootingKing-AM #1801)
• Fix white dashboard bug on Linux (by @zarik5)