Video wallpaper, pin/hide apps

What's new

• Video wallpaper. The background is now a looping 4K video of all the wallpapers, which the TV decodes in hardware. It replaces rotating 4K JPEGs on the CPU, which stalled hover highlighting. The homescreen layout is unchanged.
• Pin and hide apps. Open the app drawer and press Edit (bottom right) to pin/unpin apps on the bottom bar and hide/show apps in the drawer. Settings are saved and kept between launches. The old hardcoded bar list is only the default until you change it.
• Clock fix. The clock reads local time instead of calling the system service every second, so it no longer lags or skips seconds.
• Smoother hover. Each app tile now repaints on its own, which fixes lag when moving the pointer quickly across many apps.
• Builds out of the box from a plain clone (QwQwebosTV.js is vendored instead of a submodule).

Notes

• The video is processed by the TV's picture engine and can look grainy in some picture modes. Use Game (or Filmmaker) picture mode, or turn off noise reduction / Super Resolution.
• This is a beta: it has not been tested widely. Please report anything odd.
• Building from source: run ./scripts/make-wallpaper-video.sh (needs ffmpeg) before ares-package src. Without it the app falls back to rotating the images.