Issue #24225: Within idlelib files, update idlelib module names.

This follows the previous patch that changed idlelib file names.
Class names that matched old module names are not changed.
Change idlelib imports in turtledemo.__main__.

Exception: config-extensions.def.  Previously, extension section
names, file names, and class names had to match.  Changing section
names would create cross-version conflicts in config-extensions.cfg
(user customizations).  Instead map old names to new file names
at point of import in editor.EditorWindow.load_extension.

Patch extensively tested with test_idle, idle_test.htest.py, a custom
import-all test, running IDLE in a console to catch messages,
and testing each menu item.  Based on a patch by Al Sweigart.

Lib/idlelib/configdialog.py

@@ -14,14 +14,14 @@ import tkinter.messagebox as tkMessageBox
 import tkinter.colorchooser as tkColorChooser
 import tkinter.font as tkFont
 
-from idlelib.configHandler import idleConf
-from idlelib.dynOptionMenuWidget import DynOptionMenu
-from idlelib.keybindingDialog import GetKeysDialog
-from idlelib.configSectionNameDialog import GetCfgSectionNameDialog
-from idlelib.configHelpSourceEdit import GetHelpSourceDialog
+from idlelib.config import idleConf
+from idlelib.dynoption import DynOptionMenu
+from idlelib.config_key import GetKeysDialog
+from idlelib.config_sec import GetCfgSectionNameDialog
+from idlelib.config_help import GetHelpSourceDialog
 from idlelib.tabbedpages import TabbedPageSet
-from idlelib.textView import view_text
-from idlelib import macosxSupport
+from idlelib.textview import view_text
+from idlelib import macosx
 
 class ConfigDialog(Toplevel):
 
@@ -91,7 +91,7 @@ class ConfigDialog(Toplevel):
         self.create_action_buttons().pack(side=BOTTOM)
 
     def create_action_buttons(self):
-        if macosxSupport.isAquaTk():
+        if macosx.isAquaTk():
             # Changing the default padding on OSX results in unreadable
             # text in the buttons
             paddingArgs = {}