Remove dead conditional.

CID 1224560.
Fix uninitialized pointer fields.

CID 966482.
Use the proper type for `bool`.
Fix uninitialized scalar fields.

CID 752183 and CID 752184
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...