This gets rid of quite a lot of ugly hacks around json generation.
I doubt that any real-world json parsers can parse incomplete objects, so
while it's not as nice to need to wait for the complete object, especially
for commands like `git annex info` that take a while, it doesn't seem worth
the added complexity.
This also causes the order of fields within the json objects to be
reordered. Since any real json parser shouldn't care, the only possible
problem would be with ad-hoc parsers of the old json output.
Avoid threads emitting json at the same time and scrambling, which was
still possible even with the buffering, just less likely.
Converted json IO actions to JSONChunk data too.
This makes -Jn work with --json and --quiet, where before
setting -Jn disabled those options.
Concurrent json output is currently a mess though since threads output
chunks over top of one-another.
Instead -J will behave as if it was built without concurrent-output support
in this situation. Ie, it will be mostly quiet, except when there's an
error.
Note that it's not a problem for a filename to contain invalid utf-8 when
in a utf-8 locale. That is handled ok by concurrent-output. It's only
displaying unicode characters in a non-unicode locale that doesn't work.
This allows things like Command.Find to use noMessages and generate their
own complete json objects. Previouly, Command.Find managed that only via a
hack, which wasn't compatable with batch mode.
Only Command.Find, Command.Smudge, and Commange.Status use noMessages
currently, and none except for Command.Find are impacted by this change.
Fixes find --json --batch output
Commands that want to use it have to run their seek action inside
allowConcurrentOutput. Which seems reasonable; perhaps some future command
will want to support the -J flag but not use regions.
The region state moved from Annex to MessageState. This makes sense
organizationally, and note that some uses of onLocal use a different Annex
state, but pass the MessageState into it, which is what is needed.
A bit tricky to avoid printing it twice in a row when there are queued git
commands to run and journal to stage.
Added a generic way to run an action that may output multiple side
messages, with only the first displayed.
