Previous commits removed the async loading of videos, which can be a problem for videos played in the radar widget mid-game because it can cause a lag spike. This loads the video on a separate thread and runs it on the main thread whenever it is loaded, not blocking the main thread meanwhile and allowing the game to continue while the video loads.
Also add back cancelling of already playing video and add a check to not try to run onComplete if it is null.
Somehow this would divide by 0 on the next line, not crashing but resulting in an integer overflow on `overlayHeight`, which would crash when trying to render.
Added optional padding to video frames because that's what VideoPlayerWidget expects.
Keeping the option to not use padding for other use-cases like converting frames to PNG.
Removed property backing fields where applicable, introduced C#7 syntax for properties.
Renamed a bunch of interface properties and class private members with more descriptive names.
Did some inconsequential reordering.
