Decoupled frame rate, multiple take support, audio support, etc

* Adjustable mesh frame rate (for cameras that export at a different
framerate)
* Decoupled mesh from the application frame rate
* Ability to have multiple takes in one sequence
* Takes can play progressively
* Start frame number can be adjusted
* Sync video to audio track (if using actual frame numbers when
exporting, it will sync with original audio from the video)
* Mesh visibility can be toggled (call playMesh externally)