[PVR] Feature: Confirm shutdown if PVR backend is not idle.

User story: In case shutdown is requested by the user while PVR is recordig or a  recording will start very soon (and XBMC machine potentially cannot restart fast enough), XBMC refuses to shutdown, but shows a Yes/No dialog to the user explaining that PVR is currently not idle and asking the user to shut down anyway. If user does nothing for 10 secs, the dialog will autoclose and shutdown will be cancelled.

Purpose: This is very useful to prevent accidentally stopped recordings.

BTW: This feature has been discussed from time to time in the forums and there were some (hacky) addons around to implement this, but no clean implementation (which IMO can only be done inXBMC itself.)
hold on, I said that it can't be used by default, as your original PR did. that would make it very annoying for users with multiple frontends sharing a single backend. and since each new setting added kills a fluffy bunny, an implementation without introducing new settings definitely has my preference.

why would we need a new setting if we know the backend is on localhost and is recording?