Standalone: Handle Tkinter giving "ImportError" only once.
Standalone: Handle Tkinter giving "ImportError" only once.

* When multiple modules try to import it, an extension modules produces
  an error, but only for the first attempt, not for later ones, which
  then succeed when they should not.

* This fights those zombie modules and makes standalone work for systems
  without python-tk installed.

kayhayen/Nuitka,kayhayen/Nuitka,kayhayen/Nuitka,kayhayen/Nuitka