CDDA Reader: Remove a useless conditional.

A 4-bit field can't hold value greater than 0xf.

Fixes CID 965921.
MPC Audio Render: Mark some member variables as such (cosmetics).
MPC Audio Render: Be more careful when dereferencing pointers.

Fixes CID 965990 and 966169.
CTextFile: Remove a useless check against 0.

Unsigned integers are always greater than or equal to 0 by definition.

Fixes CID 966071.
PlayerCaptureDialog: Don't shadow function argument with local variable.
CDDA Reader: Check index more carefully before using them.

Fixes CID 966205.
Don't force any background color for the Shockwave graph.

This commit fixes #1747.
ISR: Render text subtitles relative to the video frame when in doubt.
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...
Fix: x86 and x64 versions conflicted over file associations.

4f465cf8b81f1da800b1bfc57cc48e317d24fbb5 was incomplete for Vista+.

This commit fixes #4064.
Auto mode for relative to.