M Bindings.py

M PyShell.py
M config-keys.def
M configHandler.py

1. Clear any un-entered characters from input line before printing the
   restart boundary.
2. Restore the Debug menu: There are now both Shell and Debug menus.
3. Add Control-F6 keybinding to Restart Shell.
4. Clarify PyShell.cancel_check() comment.
5. Update doc string for Bindings.py and re-format the file slightly.

Lib/idlelib/configHandler.py

@@ -522,6 +522,7 @@ class IdleConf:
             '<<history-previous>>': ['<Alt-p>'],
             '<<interrupt-execution>>': ['<Control-c>'],
             '<<view-restart>>': ['<F6>'],
+            '<<restart-shell>>': ['<Control-F6>'],
             '<<open-class-browser>>': ['<Alt-c>'],
             '<<open-module>>': ['<Alt-m>'],
             '<<open-new-window>>': ['<Control-n>'],