Complete refactor for segment loading to load based on time + buffered data. Automatically responds to seeks. Changes dl rate based on buffer size. PlaylistLoader now changes playback rate based on ready state + events. SegmentLoader now automatically first loads initialization then requested segment if a bitrate change has occurred. SourceBufferDataQueue now handles arrays of segments being passed to it. Various bug fixes. Removed window module since no longer a dependency. Removed old download rate approach since no longer using it.