Add structures and API for unified output definition and multiple
formatting backends. Currently there's plain text and json.
The format of each row is defined in struct rowspec, selected using a
key and formatted according to the type. There are extended types for
eg. UUID or pretty size, while direct printf format specifiers work too.
Due to different nature of the outputs, the context structure members
are not always used.
* text output mostly uses indentation and formats the name to a given
width
* json output tracks nesting depth and keeps stack of previous groups
(list or array) and how many member have been printed, as the
separators are allowed only between values and must not preced the
group closing bracket
the nesting depth is hardcoded to 16, counting the global group
The API provides functions to print simple values and some helpers to
format more complex structures.
Signed-off-by: David Sterba <dsterba@suse.com>
3122085a79