lavfi/ebur128: use same ref for inputs and outputs.

Fixes Ticket2342.
ffmpeg: add OPT_OUTPUT to -to option.

Fix trac ticket #2355.
ffmpeg: add OPT_INPUT to -guess_layout_max.
lavfi/graphdump: fix output for unknown layouts.
examples/filtering_video: update to new API

In particular, fix crash.
examples/filtering_audio: update to new API

In particular, fix crash.
examples/filtering_*: constify AVFrame * for print_frame() and display_frame() functions
lavf/avio: fix two extreemly unreasonble typos.
lavfi/ebur128: add framelog option.
lavfi/ebur128: check histogram allocations.
avutil/frame: add AVBufferRef for qp table

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
h263dec: export qp_table

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
mjpegdec: export qp table

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
mpeg1/2: export qp table

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
vf_pp: use new API to access qp table

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