mpegts: starting to tidy up input class
linuxdvb: add complete (ish) v3 and S2 tuning calls

This still doesn't include any code to handle DVB-S, that needs further
thought on how best to configure.
linuxdvb: updated tuning/pid filtering code

All services/tables should now be opened using PES filters if the
tuner is not in full mux mode.