mpegts: fix some issues with network scanning

mux matching was far too strict and resulted in a failure to update muxes
with new modulations etc... Also frequency changes were not detected, so
there is some attempt to handle greater changes (mostly just DVB-S, could
be extended).

And where ONID/TSID are set, they are compared as an additional check.
I think it's a case of suck it and see, but on my Astra 28.2E scan this
did a nice job of cleaning up (including tying together modded) muxes.