swscale: correctly pad destination buffer in rgb conversion

Bug-Id: 772
CC: libav-stable@libav.org
Found-By: Justin Ruggles <justin.ruggles@gmail.com>
Signed-off-by: Vittorio Giovara <vittorio.giovara@gmail.com>
pixdesc: Support pixelformat aliases

Signed-off-by: Vittorio Giovara <vittorio.giovara@gmail.com>
avutil: add alias names for gray 8/16 colour spaces
avutil: rename AV_PIX_FMT_Y400A to AV_PIX_FMT_YA8

The rationale is that you have a packed format in form
<greyscale sample> <alpha sample> <greyscale sample> <alpha sample>
and shortening greyscale to 'G' might make one thing about Greenscale instead.
An alias pixel format and color space name are provided for compatibility.
avutil: add AV_PIX_FMT_YA16 pixel format
swscale: support AV_PIX_FMT_YA16 as input

Based on a long debug session with Kostya.
png: disable broken MMX/SIMD code for bpp <= 2

The decoder was producing different results when ASM was disabled.
Based on a long debug session with Kostya.
png: support reading gray+alpha at 16 bits
tiff: support reading gray+alpha at 16 bits
tiff: support reading gray+alpha at 8 bits

Signed-off-by: Vittorio Giovara <vittorio.giovara@gmail.com>
Merge commit '5420099cab1e915b191cceccec4364f54cec6e52'

* commit '5420099cab1e915b191cceccec4364f54cec6e52':
  swscale: correctly pad destination buffer in rgb conversion

Merged-by: Michael Niedermayer <michaelni@gmx.at>
Merge commit 'd2962e9f89cca6ff40f0c9d5ffc9c4397b8b1b26'

* commit 'd2962e9f89cca6ff40f0c9d5ffc9c4397b8b1b26':
  pixdesc: Support pixelformat aliases

Conflicts:
	doc/APIchanges
	libavutil/pixdesc.c
	libavutil/version.h

Merged-by: Michael Niedermayer <michaelni@gmx.at>
Merge commit 'e0d73fda361729d207e51fa2afd8ba6102e58d98'

* commit 'e0d73fda361729d207e51fa2afd8ba6102e58d98':
  avutil: add alias names for gray 8/16 colour spaces

Merged-by: Michael Niedermayer <michaelni@gmx.at>
Merge commit 'e96c3b81cadd0ba84d43b1f3a54980df3785d9a5'

* commit 'e96c3b81cadd0ba84d43b1f3a54980df3785d9a5':
  avutil: rename AV_PIX_FMT_Y400A to AV_PIX_FMT_YA8

Conflicts:
	libavcodec/libopenjpegdec.c
	libavcodec/libopenjpegenc.c
	libavcodec/raw.c
	libavutil/pixdesc.c
	libavutil/pixfmt.h
	libavutil/version.h
	libswscale/swscale_internal.h
	libswscale/swscale_unscaled.c

Merged-by: Michael Niedermayer <michaelni@gmx.at>
Merge commit 'e9abafca278f87e1ecc6d50091d99b73ff63c9a6'

* commit 'e9abafca278f87e1ecc6d50091d99b73ff63c9a6':
  avutil: add AV_PIX_FMT_YA16 pixel format

Conflicts:
	libavutil/pixdesc.c
	libavutil/pixfmt.h
	libavutil/version.h

Merged-by: Michael Niedermayer <michaelni@gmx.at>
Merge commit 'f84a1b597c29dc035b8d5529ef88c2d7ff057820'

* commit 'f84a1b597c29dc035b8d5529ef88c2d7ff057820':
  swscale: support AV_PIX_FMT_YA16 as input

Conflicts:
	libswscale/swscale_unscaled.c

Merged-by: Michael Niedermayer <michaelni@gmx.at>
Merge commit '2257165bff243534982f4ddabae4e65e2a35f2ab'

* commit '2257165bff243534982f4ddabae4e65e2a35f2ab':
  png: disable broken MMX/SIMD code for bpp <= 2

See: d1c48025a71e9e190d79115759c10f5807f4d0a7
Merged-by: Michael Niedermayer <michaelni@gmx.at>
Merge commit 'e64f0bf2d2b1347ec9461f0e82852a62e8c6ffbe'

* commit 'e64f0bf2d2b1347ec9461f0e82852a62e8c6ffbe':
  png: support reading gray+alpha at 16 bits

Merged-by: Michael Niedermayer <michaelni@gmx.at>
Merge commit 'bcc5f69b33e27b5e11aaea8304ee02f8d895cdab'

* commit 'bcc5f69b33e27b5e11aaea8304ee02f8d895cdab':
  tiff: support reading gray+alpha at 16 bits

Conflicts:
	libavcodec/tiff.c

Merged-by: Michael Niedermayer <michaelni@gmx.at>
Merge commit '60cbd6ad84de0931314030b81df87b69d6196587'

* commit '60cbd6ad84de0931314030b81df87b69d6196587':
  tiff: support reading gray+alpha at 8 bits

Conflicts:
	libavcodec/tiff.c

See: f746f3790168bf898b629942868bda703e7f1045
Merged-by: Michael Niedermayer <michaelni@gmx.at>