Convenience node adders, based on issue #497

[xulman]

this is a followup of the issue #497, it is

• deprecating addChild()
• cosmetics: injecting @Deprecate tag to removeChild()
• adding a shortcut variant of addNode()

demo example

			SciView sv = SciView.create();

			Sphere j = new Sphere();
			j.setName("addnode");
			sv.addNode(j, false);
			//NB: renders already but lists not yet in the scene inspector panel

			Sphere s = new Sphere();
			s.setName("addchild");
			sv.addNode(s, j);
			//NB: only now all "pending" added nodes will get listed in the inspector panel

[kephale]

Looks good to me!