Add generic version of a canvas MFD (based on the F-15)
It has a fairly simple class structure and hopefully is reasonably easy to understand; Thorsten's using it on the Shuttle and Hooray mentioned that it'd be a good idea to make it generic. It provides a device, that has pages and a set of buttons. The set of buttons control the page that is selected (i.e. a menu). Each page has its own set of menus. A menu defines a label and a page that is displayed. I intend to document it on the wiki once its added.
