* core: option to show group as sender of chat item (for the initial items, e.g. welcome message)
* add chat item to contact request chats
* return AChat for prepared chats and contact requests
* update iOS api types, show prepared contact as blue, show preview info when content message is not available (previously was showing feature item)
* ios: remove ContactType
* ios: show group as sender, fix avatar not showing when member message sequence starts with merged items
* ios: update compose UI for all connection scenarios
* address settings
* ios: address settings UI
* fix tests
* fix tests 2
* ios: fix minor issues
