ICE-9446 added support for ace:multiColumnSubmenu to ace:menu; multi-column submenus are supported in tiered and plain menus as flyout submenus, and a special case is supported when the menu only contains a single ace:multiColumnSubmenu

git-svn-id: http://anonsvn.icesoft.org/repo/icefaces3/trunk/icefaces@37291 1de00972-ac04-4911-a46b-06793c8d78d9