Custom rendering of menu-items with custom event-handlers per menu-item

Ref this thread: http://groups.google.com/group/liftweb/browse_thread/thread/91e663dd5ccd92f6/d6ef9177210b8e1d

It would be nice to be able to have complete control over how menu-items are rendered. Today's Menu.builder is less optimal as it's impossible to generate customized events on the generated anchor-tag for each menu-item. Sometimes one wants to have some other markup (div, span etc.) for special menu-items so it would be nice to have that option too.

Start by reading the linked discussion and examining today's Menu.builder behavior. Clarify how per-menu-item event handlers and alternate markup such as div or span should be represented; done means menu items can render customized markup and events without the current builder limitation.

Written by the indexing model from the issue text.