MP1-4420 : Fix Startup delay setting on resume (http://wiki.team-mediaportal.com/REDIRECTS/MediaPortal.Configuration.Sections.GeneralStartupResume). Handling if system send multiple POWERBROADCAST event by not mix the event but wait first event finish before starting the second, in some case it can lead to MP freezed on start.
First tests with powerbroadcast message thread
PowerBroadcast messages are handled by a thread to allow delay on resume
Merge remote-tracking branch 'remotes/upstream/MP1-4420-BUG-Startup_resume_not_used_correctly_fix_multiple_POWERBROADCAST' into 1.7.0Fork-BDJ

Conflicts:
	mediaportal/MediaPortal.Application/MediaPortal.cs
Fork : Update libbluray.