CS50-inspired paella theme. Includes:

* Styling, color, and icon improvements.
* Use cs50 theme by default, disabling others
* Workflow and tooling improvements
* Add playback rate plugin
* Toggle between four simplified layouts / profiles
* Optimize video profiles for our aspect ratios
* Update git strategy RE the upstream git process refactor
* Style the frameControl plugin, subtle background gradient
* Disable controls autohiding by setting the timeout to a huge value
* Create the "total duration" plugin, show in the control bar