Disable bookmark menu items when unavailable + the code formatter for Haxe

![](http://i.imgur.com/pfbLIWw.png)

Only "toggle bookmark" is now available when the current document has no bookmarks.
Putting this here is kind of a hack, but I haven't managed to get it working when doing at right when loading the document (for example at the end of `AddEditorControls()`).