* Fix ME and SE versions of details dialog not displaying their content properly after change to QDockWidget
* Add option to toggle titlebar and orientation of titlebar in preferences dialog
* Fix setting layout on PE details dialog window while layout already set, by removing the self (parent) reference in constructing the QSplitter
- Format all files with black
- Update tox.ini flake8 arguments to be compatible
- Add black to requirements-extra.txt
- Reduce ignored flake8 rules and fix a few violations
Ticket #379 reports crashes on quit due to `willSavePrefs` being called
when result and details dialogs are already freed. I can't reproduce the
crash, but it's still a bad idea to rely on the timing of
`aboutToQuit()` to launch this process.
This commits uses a more predictable place to emit `willSavePrefs` and
I'm pretty sure it will fix the crash at #379.
