mpegts: correct close on -1 spotted by btwe
subscription: fix full mux sub hook

I'd added this so that ALL mux subs tried to use fullmux reception. This was
clearly not what was intended as the only time this is needed (at present)
is when subscribing for muxdump from the webui.
mpegts: put muxes not yet scanned to front of Q and those that have to the back
mpegts: add input prioritisation

I've also changed some function names for consistency.