menubar: massive refactor for readability

Emergent in the menubar widget since my first
patchfix (9f53e0a) is that there is significant
behavioral difference between:

* A menuitem that *does* have a sub-menu
* A menuitem that *does not* have a sub-menu

Typically, from an OO POV, the caller should be
able to call `menuItem.close()` on either one of
these cases and not have to bear the burden of
knowing whether or not said `menuItem` has
submenus in it.

Ergo, "properly" speaking, I would want to create
two new constructors and assign the logic there.
But the, "properly" those things should be their
own class, perhaps rightly a class that should be
part of the JQuery UI widget set.

As an intermediary measure I have tried to use a
very simple procedural style (à la C) so that the
code is small, comprehensible, and doesn't rely on
using `$.each` iteration to apply or remove
behavior to elements.  I believe, by using this
behavior, the code is much more digestible.  It
as, at the very least, for me.

Beyond the coding philosophy part of the refactor,
I attempted to bring standard sane behavior for
"menu item without submenu."  This behavior may
need to be modified as, up to the point of
writing, there has been no fully definition of
these menuItems' standard of behavior.

Author: Steven G. Harms

tests/visual/menubar/menubar.html

@@ -41,6 +41,7 @@ <h2>Default menubar</h2>
 			<li><a href="#Quit">Quit</a></li>
 		</ul>
 	</li>
+	<li><a href="#Stubby">Stubby</a></li>
 	<li>
 		<a href="#Edit">Edit</a>
 		<ul>