lavu/eval: add bitor and bitand functions

Warning note suggested by Reimar.
doc/filters: add bit-slicing example in lutyuv docs
lavfi/blackframe: add support for named options
lavfi/settb: add support for named options
ffprobe: remove deprecated frame "reference" field
lavfi/thumbnail: replace frame unref with free.

Fixes memleak spotted by FATE.
tests/eval: fix reference after b2098d2417a085d33d99738dd7f963c7b260a0bf

+10l to me, I blame the aliens.
tests/filter-metadata-scenedetect: update reference

Fix reference after f7ab23b0d0a8b72a62bd9386a1e48ccc2cf47576.
+10l to me, this time aliens are not involved.
avutil/frame: fix video buffer allocation

The padding was lost during porting from avcodec
Should fix out of array accesses

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