[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.)
Re functionality: I documented the new member function. See Application.h:

@brief Check whether kodi can be shutdown without accidentally stopping any active recordings.
@param bAskUser In case pvr backend is not idle, true to ask user what to do, false to return false.
@return True if pvr backend is not idle or user confirms to shutdown anyway.

Re "hard to follow": No problem. Will change the implementation of the new member function and of the using code to be more "positive".

No problem with renaming this member function. Do you have a suggestion for a better name?