mpegts: Added some new post start/stop routines to allow flexibility

This is required for DVB-S where the input object is actually acting as a
proxy for the frontend.
linuxdvb: early stage of getting DVB-S to work.

I've added missing config (delsys) to muxes and I've got satconf working
as a full proxy of frontend (may still be a few small issues). Satconf
is not yet doing anything useful, its hardcoded to a universal LNB and
no switch/rotor support.