Added some getters and setters, establishing support for early frame display.
I had to add the new display class, to support some properties. The display mentioned in the JavaScript reference implements display.noPrint, display.hidden, display.visible, display.noView, which supersedes the old hidden and print properties. I didn't implement the noView and noPrint, since the fields don't have this property. If we go ahead and implement it, I will change some code to make it work.
Also, it is missing the Doc.dirty, in all documents we set to false, and it means that the document doesn't need saving.