bpo-37039: IDLE - zoomheight fixes (GH-13576)

Move doc entry to match menu and refactor zoom function.
A followup patch will include a blurb.
diff --git a/Doc/library/idle.rst b/Doc/library/idle.rst
index c51cf19..bd24695 100644
--- a/Doc/library/idle.rst
+++ b/Doc/library/idle.rst
@@ -281,16 +281,16 @@
    menu. For more, see
    :ref:`Setting preferences <preferences>` under Help and preferences.
 
-Zoom/Restore Height
-   Toggles the window between normal size and maximum height. The initial size
-   defaults to 40 lines by 80 chars unless changed on the General tab of the
-   Configure IDLE dialog.
-
 Show/Hide Code Context (Editor Window only)
    Open a pane at the top of the edit window which shows the block context
    of the code which has scrolled above the top of the window.  See
    :ref:`Code Context <code-context>` in the Editing and Navigation section below.
 
+Zoom/Restore Height
+   Toggles the window between normal size and maximum height. The initial size
+   defaults to 40 lines by 80 chars unless changed on the General tab of the
+   Configure IDLE dialog.
+
 Window menu (Shell and Editor)
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^