bpo-29446: IDLE -- add explicit imports (GH-14919) (#14921)

Stop depending on tkinter import *.
(cherry picked from commit c6fd6c8)

Co-authored-by: Terry Jan Reedy <tjreedy@udel.edu>

Author: miss-islington

Lib/idlelib/editor.py

@@ -2,7 +2,9 @@
 import importlib.util
 import os
 import platform
+import re
 import string
+import sys
 import tokenize
 import traceback
 import webbrowser