Move plane/stride calculation out of the individual pixfmt converters
Support different image height/buffer height during pixfmt conversions
Do not send dwControlFlags for only the MPEG2 Chroma Location info

MPEG2 chroma location is the default for 4:2:0, and the information
is as such not really useful, and not worth the extra reconnection cycle.
Update ffmpeg
Update ffmpeg for DTS fix
Check the decoder exists before trying to decode
Disable DXVA2 Extended Format support for the overlay mixer

Overlay mixer responds badly to these flags, resulting in a black screen in some cases.
Update ffmpeg
Link against the debug runtime when building MSVC debug ffmpeg
[MPC-HC] Use our own ffmpeg clone repository.

WARNING: This should be the first custom commit in our fork and its title should not be modified.
[MPC-HC] LAV Splitter: Exhibits MKV attachments through IDSMResourceBag interface.
[MPC-HC] Tray icon: Add an optional custom callback for "show property page" events.
[MPC-HC] Fix the include directories for FFmpeg's out-of-source-tree build.
[MPC-HC] Version number: Add a "git describe based" commit number to identify the vanilla LAV Filters we are based on.

This way if we distribute LAV Filters version X.Y.Z.N, it means that our custom build is based on:
 - the stable version X.Y.Z,
 - with N official patches (which will be part of next official LAV Filters build),
 - and some custom non-official patches which are here to improve the integration in MPC-HC.