* It seems that stretching the last section automatically is a bit inconvenient on MacOS as it will grow beyond the window border.
* Keep it as it was before for now until a better solution is devised.
* Directories dialog, Results window and ignore list dialog are the three dialog windows which can now be tabbed instead of previously floating.
* Menus are automatically updated depending on the type of dialog as the current tab. Menu items which do not apply to the currently displayed tab are disabled but not hidden.
* The floating windows logic is preserved in case we want to use them again later (I don't see why though)
* There are two different versions of the tab bar: the default one used in TabBarWindow class places the tabs next to the top menu to save screen real estate. The other option is to use TabWindow which uses a regular QTabWidget where the tab bar is placed right on top of the displayed window.
* There is a toggle option in the View menu to hide the tabs, the windows can still be navigated to with the View menu items.
- 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
