contacts-list-dialog: The grid is the future, embrace it
utils: Add methods for getting the avatar

These are going to be used by both ChatContactsListDialog and
ChatConversationsList.
contacts-list-dialog: Don't load the avatars synchronously
embed: Use the default message for an empty status string
contacts-list-dialog: Ellipsize the aliases
conversations-list: Show the avatars
contacts-list-dialog: Fix the alignment of the row elements
Style fixes
Add ChatManager
client-factory: Add some default channel features
embed: Send messages