I've added a one second cache to the NSMenu proxy because otherwise the menu provider...

I've added a one second cache to the NSMenu proxy because otherwise the menu provider may be creating new instances on every method call, and when a menu is displayed, something like 24 methods are called, so that's 24 (potentially different) instances.
I also had the ITStatusItem directly set the cell's menu, rather than setting itself's menu, this way, everything will work fine if you change your mind and decide to use setMenu: instead of setMenuProvider:.