When sorting fs.DirEntries we sort by DirEntry type and
when synchronizing files let the directories be before objects,
so when the destintation fs doesn't support duplicate names,
we will only lose duplicated object instead of whole directory.
The enables synchronisation to work with a file and a directory of the same name
which is reasonably common on bucket based remotes.
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.
Before this change using --files-from would scan all the directories
that the files could possibly be in causing rclone to do more work
that was necessary.
After this change, rclone constructs an in memory tree using the
--fast-list mechanism but from all of the files in the --files-from
list and without scanning any directories.
Any objects that are not found in the --files-from list are ignored
silently.
This mechanism is used for sync/copy/move (march) and all of the
listing commands ls/lsf/md5sum/etc (walk).
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.
