PPageFormats: minor fixes.

- Make it high-dpi aware.
- Make "Set as default program" button accessible for regular users.
Video renderers setting changes

- Mark VMR-7 (renderless) as unavailable on 64-bit build. (required libs
  are unavailable)
- Change default renderer on XP to VMR-7 (renderless). It will fallback
  to system default one (VMR-7 windowed) if it fails. This change will provide subtitle
  support with default settings.
- If EVR is unavailable on Vista+ select VMR-9 (renderless) instead of
  system default one. Again it will fallback when needed, and in fact it
  should never fail.
- Move madVR higher on the list.
Fix typo introduced in 8ae02c6203ea3296406b88910bfdefbf80a8614e.
Add temporary flag to allow EC_VIDEO_SIZE_CHANGED event to stabilize
window size for 5 seconds since playback starts.

Fixes #4827
MediaInfo page: Minor cosmetics.

- Simplify a cast.
- Always use the actual size of the buffer.
Subtitle queue: Fix sluggish rendering of animated subtitles.

After 8d494fcd586c1bc75f8493d2fa68d5784394aeb3, the queue started using the time per frame to avoid rendering useless subpicture. However the time per frame we get from the filter chain can be an estimate which induces slightly misprediction in the start and end times of each frames. This can sometimes cause issues when rendering animated subtitles because the wrong subtitle is picked up.

This commit fixes those issues by using some more or less hackish work-arounds until this problem can be fixed in a cleaner way.
Don't force any background color for the Shockwave graph.

This commit fixes #1747.
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...