Replace the "reloadThis" ListModel hack by an actual signal,
works when the subtitle is displayed in more than one place
(e.g. two accounts in the same room connected).
- Fix roomList height again, now based on model.count().
All delegates are assumed to be the same height
- Properly update room list when a room is joined or left
- Catch exceptions happening in threads (futures), which previously
passed silently
- Show "Empty room?" as "<i>Empty Room</i>" + gray [?] avatar
To make the models update correctly in QML:
- ListModel and _QtModel merged
- Return a ListModelMap QObject from properties instead of
a DefaultDict → QVariantMap
- Started work on the matrix-nio backend, which will be used instead
of matrix-python-sdk for greater control and cleaner design
- Have an Application (QGuiApplication) class to habdle argument parsing
and setting some Qt properties like application name
