Describe all "users" app related events in Events class
Move "threadUpdate" event to Events class
Create "threadDelete" event
Add "threadClose" event
Add "groupCreate" event
Refactor create_group function a little
Create delete_group function
Add "groupDelete" action
Add "invitationCreate" event
Add "invitationAccept" event
Add "invitationReject" event
Encapsulate work with bans in Ban class
Add "banCreate" event
Add "banDelete" event