* remove group member
* leave group, fix remove member, tests for leave group/remove member
* delete group with test
* prevent contact deletion error when it is a group member
* support inviting the group member who left or was removed
* use small retry interval in the tests
* test multiline outputs
* create group after invitation
* add group invitation to db, show sent and received group invitations
* test creating group and sending invitation
* establish group connections (WIP)
* connect user to the inviter, notification, member classification