This replaces the `sync.Pool` allocator with lib/pool. This
implements a pool of buffers of up to 64MB which can be re-used but is
flushed every 5 seconds.
If `--use-mmap` is set then rclone will use mmap for memory
allocations which is much better at returning memory to the OS.
Cookies are handled by cookiejar in memory with fshttp module through
the entire session.
One useful scenario is, with HTTP storage system where index server
adds authentication cookie while redirecting to CDN for actual files.
Also, it can be helpful to reuse fshttp in other storage systems
requiring cookie.
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.
