code cleanup and comments

UI: CSV mode

csv_threading.py

@@ -36,6 +36,7 @@ class ExecCSVThread(Thread):
             self.parent.stop_button["state"] = "disabled"
             self.parent.reinit_button["state"] = "normal"
 
+    # setup ability to interrupt thread (https://stackoverflow.com/questions/323972/is-there-any-way-to-kill-a-thread)
     def stop(self):  # stop thread execution, can be called from another thread to kill this one
         self.__stop_event.set()