doc/decoders: Document libopencore-amrnb decoder

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
(cherry picked from commit b43860ee0c27279f2fa020ea965c03d359f8f45c)

Signed-off-by: Timothy Gu <timothygu99@gmail.com>
doc/decoders: Add libopencore-amrwb decoder doc

Signed-off-by: Stefano Sabatini <stefasab@gmail.com>
(cherry picked from commit 83647ace735d1707d4b28345ef77fefe525ea52e)

Signed-off-by: Timothy Gu <timothygu99@gmail.com>
doc/encoders: alphabetically list the encoders

Signed-off-by: Stefano Sabatini <stefasab@gmail.com>
(cherry picked from commit 934df3b0375743ae2b03168a4174edb9f88a6889)

Signed-off-by: Timothy Gu <timothygu99@gmail.com>
doc/decoders: document libopus decoder

Signed-off-by: Stefano Sabatini <stefasab@gmail.com>
(cherry picked from commit 7eb5288f17aad81d5bd1b4d3d46533e457df262c)

Signed-off-by: Timothy Gu <timothygu99@gmail.com>
doc/muxers: Add AIFF doc

Signed-off-by: Stefano Sabatini <stefasab@gmail.com>
(cherry picked from commit 4ec46b1160eb549a551823c168905b43922add31)

Signed-off-by: Timothy Gu <timothygu99@gmail.com>
doc/encoders: add libopus encoder doc

Signed-off-by: Stefano Sabatini <stefasab@gmail.com>
(cherry picked from commit 561e05136f1cbe28a79af1940aa137f70281eef4)

Signed-off-by: Timothy Gu <timothygu99@gmail.com>
doc/encoders: partially rewrite and reformat libx264 docs

Format is based on the thread:
"[PATCH] doc/encoders: Add libopus encoder doc" (06-28-2013)
http://thread.gmane.org/gmane.comp.video.ffmpeg.devel/165368/

Also merge the two option sections (Mapping and Private options).

Patch partially edited by Stefano Sabatini.

Signed-off-by: Stefano Sabatini <stefasab@gmail.com>
(cherry picked from commit 11cb697501edf6447a718d6194f0e63ec2310d39)

Signed-off-by: Timothy Gu <timothygu99@gmail.com>
doc/encoders: add libxvid doc

Signed-off-by: Stefano Sabatini <stefasab@gmail.com>
(cherry picked from commit 6b255e5e70c72aa59ff7aed74b4ee976223eb140)

Signed-off-by: Timothy Gu <timothygu99@gmail.com>

Conflicts:
	doc/encoders.texi