Spotted-by: Cristian Secară

Preliminary changes to fix postprocessing. Decoder quantizer settings can now be exported in the picture_t struct. Currently only works if the video is being decoded by ffmpeg since other codecs don't expose quantizer stuff. Please review.

Seems like it is too slow on Win32 (??). Hopefully fixes #1919.

Claims that it breaks VLC. If that is the case, I have to beliebe the
Win32 port must have some really serious problem. By the way, this
commit was the only limited yet working way for me to debug on Win32.

This reverts commit 079a3e8f.

This reverts commit 916717a7.

Revert something which never should have been commited (see bb255df4).

Still errors present, but too latE.

It is not mandatory but NIT support is better.

Only DVB-T tuner is supported (but it would be easy to add DVB-S/C).
The files scan.c/h are strictly independant of the DVB access and could
be reused for the DBA access if wanted.

Should fix the ppc crash.