mpegts: add missing mux get_title routine, fixes #2071
linuxdvb: remove full mux rx mode

There is currently no use for this feature in TVH, it was only ever added as
a means of getting internal table filtering going and with the idea of some
caching feature that's never materialised. However enabling on low performance
devices can often cause problems, so until there is a genuine use I'm removing
confusion.
http: attempt to remove pointless errors on shutdown

This is still not foolproof and I'm not 100% convinced there couldn't be an
error (including crash?) on shutdown.
mpegts: some minor changes to init / shutdown to avoid pointless errors
mpegts: add PMT monitoring option

PMT monitoring is currently disabled by default, need to decide whether
this is the correct behaviour. This should help low performance tuners.
Fixes #1986
tsdemux: hack for PCR extraction now PMT monitoring is disabled

Probably should just force PMT monitoring on for tsfile input and
only extract PCR from "known" good PID. However I've found in
practice the "real" PCR streams are typically video streams that
also include payload. So this hack works for now.
iptv: fix stupid error causing IPTV systems to fail (fixes #2067)

This occured where the IPTV system was using small packets (7 pkts
is pretty normal since it always fits in most IP datagrams)
unfortunately all my testing had been with custom generator script
that used much larger packets.