FullScreen Addon

Hi Marijn,

I have created the fullscreen addon for my CodeMirror-Eclipse (https://github.com/angelozerr/CodeMirror-Eclipse) because I embed CM in a Eclipse EditorPart with fullscreen mode.

This addon is just a copy/paste of the javascript of your demo/fullscreen.html. Here the benefit with this addon : 

1) avoid copying/pasting the fullscreen javascript of demo/fullscreen.html to manage fullscreen (just include the addon/display/fullscreen.js
2) can initialize the fullscreen with options : 

------------------------------------------------------------------------------------------
var editor = CodeMirror.fromTextArea(document.getElementById("code"), {
  ...
  fullScreen:true
}
------------------------------------------------------------------------------------------

I have created too a fullscreen.css (copy/paste the style included in the demo/fullscreen.html. I have just modified the z-index because my completion is not displayed.

I have modified the fullscreen demo with this new addon.

Hope you will like it.

Regards Angelo