* We need to set the Details Dialog's previous instance to None when recreating a new Results window
otherwise Qt crashes since we are probably dereferencing a dangling reference.
* Also fixes Results tab not showing up when selecting it from the View menu.
* Whenever the Result Window already existed and its tab was in second position, and if the ignore list tab was in 3rd position, asking to show the Result window through the View menu would add a new tab and push the Result tab to the third position (ignore list tab would then become 2nd position).
* Fix view menu Directories entry not switching to index "0" in custom tab bar.
* The close button on custom tabs cannot be hidden on MacOS for some reason.
* Prevent the directories tab from closing if the close button was clicked by mistake
* Add Directories to the View menu.
* View menu items should be disabled properly depending on whether they point to the current page/tab.
* Keep "Load scan results" actions active while viewing pages other than the Directories tab.
* 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.
