Especially if one tries to interact with all marked messages there could be
the case that not all headers are fetched yet, hence the messageInfo is still nil.
This segfaults a lot of commands which in principle only need the uid to complete.
If we switch to uids, this issue can be alleviated for those commands.
Before, we were using several IMAP-specific concepts to represent
information being displayed in the UI. Factor these structures out of
the IMAP package to make it easier for other backends to provide the
required information.
Before, the information needed to display different parts of the UI was
tightly coupled to the specific messages being sent back and forth to
the backend worker. Separating out a models package allows us to be more
specific about exactly what a backend is able to and required to
provide for the UI.
Consists of 3 functions
* Store: Access to MessageStore type
* SelectedAccount: Access to Account widget that the target widget
belongs to
* SelectedMessage: Current message (selected in msglist or the one we
are viewing)
Signed-off-by: Kevin Kuehler <keur@ocf.berkeley.edu>
