Text subtitles: Prefer wcstol/wcstod to swscanf_s for simple conversions.

wcstol/wcstod are 4 or 5 times faster than swscanf_s when parsing just one number.

Around 10% faster loading overall on my ASS test file.
Text subtitles: Much faster string tokenization.

Avoid reallocating the buffer.

Around 20% faster.
Text subtitles: Tokenize numerical values without string copy.

Around 25% faster parsing.
Subresync bar: Various cosmetics.
Subresync bar: Don't show the ampersand in "Yes"/"No" strings when not in a menu.

Also avoid reloading the same resource strings each time.
Subresync bar: Make the list control virtual for faster loading.

The list control is just a view for the subtitle data so there is no need to duplicate it into the list control.

This makes loading a subtitle into the Subresync bar nearly instant even for complex subtitle files which will now be order of magnitude faster to load.
Accept loading more than one subtitle file at a time using drag-and-drop.
"Load subtitle" dialog: fix the filter and simplify the code.

It was mostly broken for Windows Vista+ but improve the filters while at it.
Add subtitle files to Windows recently opened files only when "keep the history" is enabled.
"Load subtitle" dialog: Allow loading more than one file at a time.
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.