Hbbtv mpeg2ts 2

This is pull request 4 out of 9 and it contains updates proposed by HbbTV for the section on MPEG2-TS. See the [visual diff to silviapfeiffer/HTMLSourcingInbandTracks:master](http://services.w3.org/htmldiff?doc1=https%3A%2F%2Frawgit.com%2Fsilviapfeiffer%2FHTMLSourcingInbandTracks%2Fmaster%2Findex.html&doc2=https%3A%2F%2Frawgit.com%2Fc-alpha%2FHTMLSourcingInbandTracks%2Fhbbtv-mpeg2ts-2%2Findex.html) for a better overview than the diffs. Please ignore the (many) individual diffs contained in this request, and focus on the diffs (source and visual) alone.

**Change notes and rationale:**
* I have converted the bullet list on determining the type of track into a table to make room for DVB and ISDB, and retained the existing text in the ATSC row.
* In the ATSC row, I have changed the quoting style to be in-line with the rest of the document.
* In the DVB row, I have added the criteria for DVB streams as needed for the HbbTV profile of DVB.
* ISDB needs to be filled in by someone knowledgeable.
Let's not specify ISDB if we know nothing about it.