vf_boxblur: switch to an AVOptions-based system.
vf_crop: switch to an AVOptions-based system.
vf_cropdetect: switch to an AVOptions-based system.
vf_delogo: switch to an AVOptions-based system.
vf_drawbox: switch to an AVOptions-based system.
vf_drawtext: switch to an AVOptions-based system.
vf_fade: switch to an AVOptions-based system.
vf_fieldorder: switch to an AVOptions-based system.
vf_fps: switch to an AVOptions-based system.
Merge commit '51def31dbe5b6e857536de8fa428f263d64f3ae5'

* commit '51def31dbe5b6e857536de8fa428f263d64f3ae5':
  vf_boxblur: switch to an AVOptions-based system.

Conflicts:
	doc/filters.texi
	libavfilter/vf_boxblur.c

Merged-by: Michael Niedermayer <michaelni@gmx.at>
Merge commit 'fba0156af77b11ec99edf4ee8f511b7aaa6b1891'

* commit 'fba0156af77b11ec99edf4ee8f511b7aaa6b1891':
  vf_crop: switch to an AVOptions-based system.

Conflicts:
	doc/filters.texi
	libavfilter/vf_crop.c

Merged-by: Michael Niedermayer <michaelni@gmx.at>
Merge commit '460e7b4f6d473d9f03ed45501221f9cb209b28fd'

* commit '460e7b4f6d473d9f03ed45501221f9cb209b28fd':
  vf_cropdetect: switch to an AVOptions-based system.

Conflicts:
	doc/filters.texi
	libavfilter/vf_cropdetect.c

Merged-by: Michael Niedermayer <michaelni@gmx.at>
Merge commit '63e58c55c17d7f8b5eec9c082fe0f8edc305a24e'

* commit '63e58c55c17d7f8b5eec9c082fe0f8edc305a24e':
  vf_delogo: switch to an AVOptions-based system.

Conflicts:
	libavfilter/vf_delogo.c

Merged-by: Michael Niedermayer <michaelni@gmx.at>
ffmpeg: update error message, and make use of av_err2str() to simplify
lavfi/amerge: drop duplicated "Buffer queue overflow" message

The same message is shown already by the called function
ff_bufqueue_is_full().
doc/filters: review introductory example and explanation

In particular, fix wrong vertical mirroring command, and clarify
and extend explanation.

Based on a patch by littlebat <dashing.meng@gmail.com>.

Should fix trac ticket #2413.
Merge commit '335c31293baec6e6cf5907bd29840af3de8ff735'

* commit '335c31293baec6e6cf5907bd29840af3de8ff735':
  vf_drawbox: switch to an AVOptions-based system.

Conflicts:
	doc/filters.texi
	libavfilter/vf_drawbox.c

Merged-by: Michael Niedermayer <michaelni@gmx.at>
Merge commit '8ec464c61c46a5d088b43d24e384d6c37b7ef14a'

* commit '8ec464c61c46a5d088b43d24e384d6c37b7ef14a':
  vf_drawtext: switch to an AVOptions-based system.

Conflicts:
	libavfilter/vf_drawtext.c

Merged-by: Michael Niedermayer <michaelni@gmx.at>
Merge commit 'b9dfee9fa259dfc885508179a359dccc9e7840bd'

* commit 'b9dfee9fa259dfc885508179a359dccc9e7840bd':
  vf_fade: switch to an AVOptions-based system.

Conflicts:
	doc/filters.texi
	libavfilter/vf_fade.c

Merged-by: Michael Niedermayer <michaelni@gmx.at>
Merge commit 'a39c154049a2d0c4fb02a5c74f58d6986ec21cec'

* commit 'a39c154049a2d0c4fb02a5c74f58d6986ec21cec':
  vf_fieldorder: switch to an AVOptions-based system.

Conflicts:
	doc/filters.texi
	libavfilter/vf_fieldorder.c

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