HTSP: Add subscriptionFilterStream command
Remove accidental code
htsp: update the EPG/HTSP hookup to send channelUpdate on next event change.

Previously this was only being output if the current event was updated.
Add episodeUri and serieslinkUri to the HTSP eventAdd and eventUpdate messages.
Do not export the episode URI if it starts with tvh:// - these are just for internal use within tvh.