img2enc: add an option for overwriting one file with subsequent images

Based on a patch by Michael Niedermayer <michaelni@gmx.at>.
Cosmetics, restore alphabetic order in atomics lists.
doc: document the prores encoder options

Adapted from the author's blag.

Signed-off-by: Luca Barbato <lu_zero@gentoo.org>
Signed-off-by: Anton Khirnov <anton@khirnov.net>
lavfi/aevalsrc: switch to an AVOptions-based system.
ffmpeg: insert aformat filter with the appropriate separator.

The ',' separator is deprecated with aformat, and thus causes various
arnings when transcoding audio.
lavfi: do not warn inappropriately with aevalsrc.
ffmpeg: insert format filter with the appropriate separator.

Similar to 937325f3.
lavfi/amerge: switch to an AVOptions-based system.
avfilter/f_select: use AVFrame metadata accessor function

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
avienc: fix overflow of audio sample count

Fixes an overflow of the sample count field within the audio stream header
chunk if audio stream data exceeds 2GB.

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
lavfi/removelogo: switch to an AVOptions-based system.
lavfi: add const to AVFilterContext.filter.

lavfi should never modify the filter through that pointer.
lavfi: add const to the pads parameter of avfilter_pad_get_name/type
lavfi: merge avfiltergraph.h into avfilter.h

We do not support using filters without AVFilterGraph in practice
anyway, so there is no point in pretending we do.
lavfi: replace avfilter_open() with avfilter_graph_alloc_filter().

Since we do not support "standalone" filters not attached to an
AVFilterGraph, we should not have a public function to create such
filters. In addition that function is horribly named, the action it does
cannot be possibly described as "opening" a filter.
lavfi: deprecate avfilter_graph_add_filter().

Since this function adds a standalone filter to a filter graph and we do
not support creating such filters, there is no reason for this function
to exist.
lavfi: add AVFilterContext.graph.

It will be useful in the following commits.
lavfi: make avfilter_free() remove the filter from its graph.
lavfi: add avfilter_init_str() to replace avfilter_init_filter().

Drop the unused opaque parameter from its signature.
lavfi: add avfilter_init_dict() for initializing a filter with a dict.