* Use advanceWidth to get the with of the original text

Co-authored-by: Nicolas Werner <nicolas.werner@hotmail.de>

fixes #881

* making userName_ an AbstractButton should make it play nicely with the ListView

* make Avatar an AbstractButton

* make userName_ in Reply.qml an AbstractButton

* use alias for avatar background color and fix margin of username in reply

Co-authored-by: DeepBlueV7.X <nicolas.werner@hotmail.de>

fixes #529

fixes #519

Showing the bootstrap state and showing there are unverified devices is
still missing.

We explicitly set a parent. We can't assign to
ApplicationWindow.transientParent though, only to
Window.transientParent, so we just call setTransientParent in C++.

The actual reuseItems is still blocked on a few upstream bugs.

fixes #507

This reverts commit 74e32dd9.