bpo-29446: IDLE -- add explicit imports (pythonGH-14919)

Stop depending on tkinter import *.

Author: terryjreedy

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