[mythtv-cmyth] Handles extended TS stream: M2TS, ATSC(208)

At first synchro it check TS stream and select packet size depending of its type.
Encapsulated TS packet is not affected ans keep 188 bytes. GoNext() will move
to next TS packet and will discard unused data, using selected size.

- M2TS counts 192 bytes
- ATSC counts 188 or 208 bytes depending of source
[mythtv-cmyth] Cosmetics in elementaryStream.cpp