lavfi/unsharp: use named options, and add missing checks on matrix size values

In particular, avoid out-of-buffer access and crashes with too big
values, and rework documentation accordingly.
doc/filters: itemize unsharp examples

Also drop pointless example.
lavfi/unsharp: extend range for amount values, to reflect the behavior of mp=unsharp

Also update the documentation accordingly, and suggest a meaningful range.
lavfi/kerndeint: use aligned linesizes for the temporary buffer.

This improves the performances just enough to match mp=kerndeint.

Signed-off-by: Stefano Sabatini <stefasab@gmail.com>
lavfi/kerndeint: move is_rgb_packed definition to the internal context

No need to recompute it for each new frame.
lavfi/yadif: remove unnecessary cast

Finish what 99162f8 started

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
lavfi/yadif: support 9, 12, and 14 bits per pixel

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