EVR renderers: Query the IBaseFilter interface of the EVR only once.

Calling QueryInterface insides those functions leaded to deadlocks in some cases.

Refs: #4213.
Fix a deadlock when starting MPC-HC in D3D fullscreen and auto-changing the monitor mode.

This commit fixes #4213.
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.
Cosmetics: Use better IDs from the resource strings.