Move freeze support to very top level.

From now on, to start the GUI from `PyCharm` run the `release/src/runPytrnsysGui.py`
script.

release/src/runPytrnsysGui.py

@@ -1,3 +1,11 @@
+import multiprocessing as _mp
+
 import trnsysGUI.gui as _gui
 
-_gui.main()
+if __name__ == "__main__":
+    # Support freezing using PyInstaller, see
+    # https://github.com/pyinstaller/pyinstaller/wiki/Recipe-Multiprocessing and
+    # https://docs.python.org/3/library/multiprocessing.html#multiprocessing.freeze_support
+    _mp.freeze_support()
+
+    _gui.main()

trnsysGUI/gui.py

@@ -1,5 +1,4 @@
 import logging as _log
-import multiprocessing as _mp
 import pathlib as _pl
 import sys as _sys
 
@@ -81,12 +80,3 @@ def exceptionHook(exceptionType, value, traceback):
         _sys.exit(-1)
 
     _sys.excepthook = exceptionHook
-
-
-if __name__ == "__main__":
-    # Support freezing using PyInstaller, see
-    # https://github.com/pyinstaller/pyinstaller/wiki/Recipe-Multiprocessing and
-    # https://docs.python.org/3/library/multiprocessing.html#multiprocessing.freeze_support
-    _mp.freeze_support()
-
-    main()