Passthrough original PAT/PMT packets to the passthrough muxer, and include these in the output stream instead of building them ourselves.  A new DVR config option allows the user to specify if these are passed through unmodified, or if they are rewritten to exclude services (in the case of the PAT) or streams (in the case of the PMT) not included in the output stream.

NOTE: This currently only works when the adapter is running in Full Mode - in filtered mode, no TS filters are currently set for the PAT and PMT packets, so the resulting transport stream will be missing them.
Fix for scrambled streams - st is NULL for PAT/PMT streams, which are never scrambled.