updates to MPEG-2 TS item 5.
In note on Matroska text tracks make sure to use 'data' attribute for
DataCue instead of 'text' attribute, which will get removed.

Also make sure the WebM reference works with specref.
Merge pull request #3 from silviapfeiffer/DataCue

Data cue
removed local bib and added as yet to be specified to CEA708Cue and SCTE27Cue
Merge pull request #2 from boblund/master

updates to MPEG-2 TS item 5.