Merge relevant parts of PR#255 to complete the implementation of PAT/PMT passthrough, with the option of rewriting the PAT and PMT so the PAT only contains a reference to the included service, and the PMT only contains references to the included streams.  This still needs more work - the PMT PID is being passed to the muxer as zero the first time a channel is streamed after tvh starts, and the PMT rewrite code fails if the PMT spans multiple TS packets