Add return values to events and method callbacks. This makes it
possible to pass any error or async return value.
Add sync/done/error in both directions so that both proxy and resource
and perform/reply sync and produce errors.
Return a SPA_ASYNC from remote method calls (and events), keep the
sequence number in the connection.
With the core sync/done we can remove the client-node done method and
it's internal sequence number along with the seq number in method calls.
We can also use the method/event async return value to perform a sync
with as the unique sequence number for this method.
Add sync method and done/error event to proxy and resource.
Remove the spa_pod_iter helpers
Remove builder/parser vararg recurse option, you have to
manually recurse into structures when needed. This simplifies
things a lot.
Pass spa_pod_frames to builder and parser explicitly, we don't
have to keep an internal stack anymore.
The parser is now almost a mirror image of the builder.
Make the parser safer when iterating over objects, add functions
to check and get pod contents in a safe way.
Make the builder return errno style results on errors
Improve performance of object properties when they are stored and
retrieved in the same order.
Add many more tests for the builder and parser
Add some benchmarks
