Playlist: Ensure the "close" command is properly routed with all safety tests.
Update the solution for Visual Studio update 3.
Comment out some unused variable assignments.

Those can be useful if the functions are extended one day.
Don't force any background color for the Shockwave graph.

This commit fixes #1747.
Why "C:\tmp.srt"?
WebUI: Inform the web interface that no audio stream is available.
WebUI: Make use of new [hasaudio] info.
What the hell was intended here?!

Trying to make some sense of that code. Without much luck so far...