md5sum, sha1sum are used by rclone.
cd, pwd improve the support for RemoteFiles mobile app.
These commands are all implemented inside SFTPGo so they work even
if the matching system commands are not available, for example on Windows
added matching permissions too and a new setting "setstat_mode".
Setting setstat_mode to 1 you can keep the previous behaviour that
silently ignore setstat requests
an user can now be disabled or expired.
If you are using an SQL database as dataprovider please remember to
execute the sql update script inside "sql" folder.
Fixes#57
Nicola Murino