[Users] Claws release 4.1.0, group mail sharing disabled

[mnieuw at zap.a2000.nl]

Thanks for looking at it.

I wonder what policy should be behind chmod. In my thinking,
if a file is copied, the _destination_ folder determines access rights.

For instance, in a shared system, where mail messages are normally rw
for owner and group, you could have a "private" folder, which has rw
for owner only. Or there could be an archive folder, with only
"read" rights for owner/group, so if a msg is moved from say Inbox to
Archive, it's access rights get adapted.

When creating a new message, I think access rights of that message
while in the tmp directory should simply be 0600. Only when it is
copied to a destination folder should the access right be set according
to the preferences.

MatN