riff: Support decoding png in avi (ImageJ)
dpx: always write the image offset

According to the DPX file format description found at
http://www.fileformat.info/format/dpx/egff.htm the ImageElement part of
the GenericImageHeader also contains an an offset to the real image data
beside the same member that can be found in the GenericFileHeader.

Libav keeps this member empty (=0) while some applications expects it to
be filled properly. FATE test updated accordingly.

Bug-Id: 742
Signed-off-by: Vittorio Giovara <vittorio.giovara@gmail.com>
Allow reading of growing avi files (currently being written)

This uses the RIFF header stored size to figure out the expected AVI
file size, instead of the actual file. To work fully it requires handling
failed avio_seek() instead of assuming they always succeed.

Some fate file has been cut off and contains half a frame at the end which
previously was not output during demuxing. This frame is now output to
encoder, thus the fate diff update.

Bug-Id: 261
Signed-off-by: Vittorio Giovara <vittorio.giovara@gmail.com>
vf_frei0r: do not increment string if it reached the end

Bug-Id: 778
CC: libav-stable@libav.org
h264: increase MAX_SLICES to 32

H264 streams from CounterPath Bria and some Cisco phones need an
increased pool for correct decoding.

Bug-Id: 645
Sample-Id: bria-h264.mka
mov: cosmetics: reorder the list of tags

Alphabetically order the list by the tag to facilitate the insertion of
new ones.
mov: parse @PRM and @PRQ metadata tags

These tags describe the product and quicktime library version respectively.
They originate from Adobe Premiere, but also some other programs use them.
Contrary to other tags, they contain 'raw' data which is not to be
interpreted as iso639 or mac strings.

Based on a patch by Peter Ross <pross@xvid.org>.
mov: parse XMP metadata on demand

The Extensible Metadata Platform tag can contain various kind of data
which are not strictly related to the video file, such as history of edits
and saves from the project file. So display XMP metadata only when the
user explicitly requires it.

Based on a patch by Marek Fort <marek.fort@chyronhego.com>.
mov: expand the list of parsed metadata tags

Based on L-Smash code by Yusuke Nakamura <muken.the.vfrmaniac@gmail.com>.
mov: further expand the list of parsed metadata tags

Signed-off-by: Vittorio Giovara <vittorio.giovara@gmail.com>