Returns the value corresponding to key in the preference file if it exists.

	// Simple scripts that creates an empty window and remembers the position and size
	// of the created window.
	class RememberPosition extends EditorWindow {
		var width : float = 300;
		var height : float = 300;
		var x : float = 100;
		var y : float = 100;
		@MenuItem("Examples/Remember position")
		static function Init() {
			var window = GetWindow(RememberPosition);
			window.Show();
		}
		function Awake() {
			width = EditorPrefs.GetFloat("EditorWindowWidth", 300);
			height = EditorPrefs.GetFloat("EditorWindowHeight", 300);
			x = EditorPrefs.GetFloat("EditorWindowX", 100);
			y = EditorPrefs.GetFloat("EditorWindowY", 100);
			position = Rect(x, y, width, height);
		}
		function OnDestroy() {
			EditorPrefs.SetFloat("EditorWindowWidth", width);
			EditorPrefs.SetFloat("EditorWindowHeight", height);
			EditorPrefs.SetFloat("EditorWindowX", x);
			EditorPrefs.SetFloat("EditorWindowY", y);
		}
		function OnGUI() {
			if(GUILayout.Button("Close"))
				this.Close();
		}
	}