This includes: handling of CatAnimation(s) generation, storing a
reference to the iframe's contentDocument, and providing methods for
acquiring the body and animations. elements-view and animations-view now
properly use this information via the project-focused and project-loaded
events.
This element provides a timeline that can be used for playback, keyframe
position visualization, and more!
Also added light testing code before the more major refactor of data
into the Project itself rather than being handled so directly by the
animations or elements tree modules (and other modules soon enough).
kts of kettek (nyaa)