The name was a relict from the very first day of project structuring,
but this name here makes for much much nicer tab-completing to source
file names...

No more "invisible" link, added tooltips

Now our main menu items all have icons and are discerned from
items macOS adds automatically.
Slightly more stringent naming.

This gets rid of an inconsistency where on macOS CMD+H was
already reserved for hiding the window. It's nicer anyway
and we get rid of an almost empty menu ("window").

... of the main windows in place (unless of course the settings are
reset).

Clicking "reset" in the Settings window should now behave the same as if
the settings file was deleted manually before starting, i. e. restore
all defaults immediately.

This layout should be well known and unsurprising to users, and the
ability to just cancel if something was changed by accident is also
nice.
Also, all windows now have reasonable minimum sizes.

Maybe something like this should also be done when saving...

Otherwise, window size settings etc. would be saved as-is on the next
program quit, making clearing these automatic position settings not
very effective (would have to go through command line args).

This feature has been broken with a commit in April... now it should
work again.
I. e.: If unknown keys are read in, they will be shown (and highlighted
as invalid) in the Preview Editor and also saved back out to the file
system.

There are potentially two warnings the user can cancel (file exists
and unsaved changes); for the latter the internal file path would be
set even if the user has cancelled. This has been fixed.

Missing INI keys are now listed more user friendly. If the user cancels
out of saving, the first missing key is jumped to and highlighted in
Inishell.

And minor cleanup

'Quit' does not send a closeEvent, so do it in the destructor.

Intermediate commit - to tune and to re-fix on other platforms

Clearing dynamic panels was not respecting the message box result

Now the user can individually turn off the confirmation dialog for when
a) an application has been opened, nothing was changed, and it is closed
again
b) an INI file has been opened, changes were made, and the application
is closed

This is nice because one of the messages could be annoying while the
other could be quite useful.

In addition to the command line --clear there is now a GUI button for
this.

But - allow not to warn again.

This way it can easily be re-used.

And remove obsolete function

also bigger default size