the currently released versions fail sometimes in encrypting to ecc keys,
see #1313, the issue is about to be fixed,
however, we should not generate ecc keys until the
fix is rolled out - otherwise new users will get encryption errors every some
messages if their counterpart is not yet using the most recent version.
we can start generating ecc keys a few weeks after the fix is rolled out.
up to now, Chat-Group-Member-Added and -Removed commands
result in a complete recreation of the memberlist
by collecting all addresses from the From: and To: headers.
this easily results in missed and accidentally removed members,
esp. when several people at the same time scan a qr code to join a group.
this commit changes the behavior of adding members by
not removing members on the Chat-Group-Member-Added command.
instead the existing memberlist is conjuncted
with the memberlist seen in the message.
only adding the member from the Chat-Group-Member-Added
seems not to be sufficient - imaging a group of Alice and Bob:
- Alice adds Claire
- Bob adds Dave _before_ seeing that Alice added Claire
- Dave would never get the information that Claire is in the group
wrt Chat-Group-Member-Removed: this command
does no longer recreate the memberlist but just remove _exactly_ the member
mentioned in the header. there are situations, where a just removed member
will be readded by out-of-order-messages, however, compared to missed
members, this is seems to be acceptable - also as this is more visible
and easier to fix (just remove the member again).
might be that, in practise, this is not a big issue. while adding members
is typically done in masses on bootstraping a group,
this is typically not true for removing members.
