JVET-N0400: Signal max number of triangle merge candidates
JVET-N0400, JVET-N0447, JVET-N0500, JVET-N0851: Signal max number of triangle merge candidates, align triangle merge candidate number and regular merge candidate number
JVET-N0400, JVET-N0447, JVET-N0500, JVET-N0851: Signal max number of triangle merge candidates, align triangle merge candidate number and regular merge candidate number