Hook everything up to run the GUI on top of the kernel.

Okay things kinda sorta work. Both Bochs and QEMU now boot into GUI mode.
There's a ton of stuff that doesn't make sense and so many things to rework.

Still it's quite cool to have made it this far. :^)

Widgets/WindowManager.h

@@ -34,6 +34,8 @@ public:
     void repaint();
     void move_to_front(Window&);
 
+    static void initialize();
+
 private:
     WindowManager();
     ~WindowManager();