The --no-traverse flag was not implemented when the new sync routines
(using the march package) was implemented.
This re-implements --no-traverse in march by trying to find a match
for each object with NewObject rather than from a directory listing.
--max-backlog controls the queue length.
Add statistics for the check/upload/rename queues.
This means that checking can complete before the uploads which will
give rclone the ability to show exactly what is outstanding.
The purpose of this is to make it easier to maintain and eventually to
allow the rclone backends to be re-used in other projects without
having to use the rclone configuration system.
The new code layout is documented in CONTRIBUTING.
