- For encrypted segments, PMT specified by SAMPLE-AES specification is
generated.
- Remove time_scale_ field from TsWriter. It is not used.
- Move ContinuityCounter to a separate file.
- Add ProgramMapTableWriter and implementations.
- continuity_counter is incremented for PAT and PMT.
Change-Id: If0dd0990203cb6990f39a6832048bdc3ff08decd