doc/filters: add quick emboss example

Signed-off-by: Paul B Mahol <onemda@gmail.com>
doc/filters: update volume options description.
avfilter/asrc_aevalsrc: check correct variable

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
lavfi: remove now unused args parameter from AVFilter.init

Conflicts:

	libavfilter/avfilter.c
	libavfilter/vf_drawtext.c
	libavfilter/vf_lut.c
	libavfilter/vf_select.c
	libavfilter/vf_setpts.c
	libavfilter/vsrc_color.c
	libavfilter/vsrc_movie.c

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
lavfi: remove now unused args parameter from AVFilter.init and init_opaque

This is mostly automated global search and replace

The deprecated aconvert filter is disabled, if it still has users
it should be updated

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