lavfi: port MP il filter

Signed-off-by: Paul B Mahol <onemda@gmail.com>
lavfi: remove mp=il filter

Native il video filter is now available.

Signed-off-by: Paul B Mahol <onemda@gmail.com>
lavfi/il: fix typo in Copyright

Signed-off-by: Paul B Mahol <onemda@gmail.com>
imgconvert: add get_pix_fmt_score()

get_pix_fmt_score() returns a score representing the amount
of loss when converting a pixel format

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
imgconvert: use get_pix_fmt_score in avcodec_find_best_pix_fmt_of_2()

This fixes various poorly choosen pixel format cases.

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>