helper utility synctool_list prints all info needed for upload
upload uses RemoteStat info to create leading dirs

including mode and ownership
translate remote owner/group to local uid/gid

unless rsync —numeric-ids is used
added module pwdgrp for pwd+grp code
it's the gid
upload uses module pwdgrp
syncstat uses module pwdgrp
small fixes
upload relays error message from synctool_list
Merge branch 'list-only'

upload now uses synctool_list.py to get remote stat info
The remote stat info is used when creating leading directories in the repos
Also added a module pwdgrp, which caches uid/gid/user/group information
use "is None"