Set the default for delete-exitfunc in config-main.def to True to handle

abnormal exit situations cleanly, especially stuck user threads.  Future
plan is to intercept the user's atexit functions and run them under
IDLE's control.

Lib/idlelib/config-main.def

@@ -43,7 +43,7 @@ editor-on-startup= 0
 autosave= 0
 print-command-posix=lpr %s
 print-command-win=start /min notepad /p %s
-delete-exitfunc= 0
+delete-exitfunc= 1
 
 [EditorWindow]
 width= 80