convert to more UI friendly buttons
adds initial TTML support
adds a verification that TTML document conforms to timing and structural constraints
fixes IndexSizeError when removing TextTrackCue's in TextTrackExtensions.deleteCues
resets textSourceBuffer when switching mpd's
ttml bugs fixes
handles ttml parsing errors
fixes structural constraints check
adds test for 'profile' element to TTMLParser.passStructuralConstraints
fixes jshint error
moves live edge search logic into new class LiveEdgeFinder
improves playback stalling logic
moves representation updating logic into RepresentationController
moves scheduling logic into ScheduleController
fixes bufferLevelUpdated notification
fixes type parameter that is passed to representationController.updateData
fixes closed captioning
fixes "system.notify is not defined" in liveEdgeFinder
sets correct indexHandler for ScheduleController
adds additional check for SourceBuffer existence after appending segments