This generalizes the previous work on disposition printing.
Disposition flags are shown in a dedicated section, which should improve
output intellegibility, extensibility and filtering operations.
This breaks output syntax with the recently introduced disposition
printing.
Add "data" and "extradata" attributes to the schema.
Add "tag" element in "streams".
Print extradata before tags to avoid closing the element.
Fix trac ticket #1588.
Add -show_frames option to ffprobe.
Partially based on the work of Thomas Kuehnel <kuehnelth@googlemail.com>
for SOCIS 2011.
The wicked idea of creating a special "packets_and_frames" container for
structured formats (JSON and XML) comes from Clément.