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.
I was hoping that there might have been some ISDB expertise among the the W3C participants, as typically the Japanese electronics firms are more active with Japanese experts in your organisation. In HbbTV, we typically see European colleagues from the Japanese companies.

If there should be no expertise available, I agree that we should not have an empty ISDB section in the published spec..