Simplify and optimize HourlyIncideModel

Don't store the layed out lines. This doesn't change the number of
times layoutLines method is called, since in any cases the ListView will
request only once each row/data combination (unless the model was reset
or dataChanged was called).

This has the advantage of simplifying the code a bit as we have less
state to manage.

To optimize the runtime instead, we reduce the refresh internal on non
displayed pages and use dataChanged instead of resetting the model
completely.

- Add Role suffix to roles
- use Q_UNREACHABLE
- assert on invalid index
- Simplify connect syntax