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>
Merge commit '9e6b5e61a0c91e25e298d0a21b189c4c95443795'

* commit '9e6b5e61a0c91e25e298d0a21b189c4c95443795':
  img2enc: add an option for overwriting one file with subsequent images

Conflicts:
	doc/muxers.texi
	libavformat/img2enc.c

Merged-by: Michael Niedermayer <michaelni@gmx.at>
lavfi/aspect: switch to an AVOptions-based system.

This is heavily based on 2831b307 by Anton Khirnov <anton@khirnov.net>
lavfi: deprecate aconvert.

This filter is not required anymore with aformat. Drop it at next bump.
Merge commit '93e65e9a6c0895f869752a66731d9b2ec3916467'

* commit '93e65e9a6c0895f869752a66731d9b2ec3916467':
  Cosmetics, restore alphabetic order in atomics lists.

Conflicts:
	libavutil/Makefile

Merged-by: Michael Niedermayer <michaelni@gmx.at>
Merge commit 'f223ad1e000d56ef5231a3b1fc00495b538a9ed6'

* commit 'f223ad1e000d56ef5231a3b1fc00495b538a9ed6':
  doc: document the prores encoder options

Merged-by: Michael Niedermayer <michaelni@gmx.at>
lavfi/aspect: fix d2q convert in init.

Regression since git 71ef1ec7b.
doc/filters: update hue command syntax after recent update
doc/filters: fix fade-out hue saturation expression in sendcmd example
avcodec: rename prores encoders

Using the first names of authors sounds somewhat unprofessional
and might be considered offensive which is not intended.
The new names use the initials of the authors due to simplicity
and the possibility to apply it consistently without the need
to find political correct names for each future case where
alternative codecs might exist. Also its shorter ...

If someone has a better idea, like maybe 2 random letters
and people prefer it then iam happy to switch to that ...

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
doc/encoders: Clarify that there are 2 prores encoders

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