Split TextViewer class into ViewWindow, ViewFrame, and TextFrame classes so that instances
of the latter two can be placed with other widgets within a multiframe window.
Patch by Cheryl Sabella.
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.
Serhiy Storchaka
terryjreedy
csabella
Victor Stinner
Jelle Zijlstra