Merging r6426 through r6466 from trunk to ogl-es branch

Note: Updated IShaderConstantSetCallBack not yet supported by ogl-es drivers


git-svn-id: svn://svn.code.sf.net/p/irrlicht/code/branches/ogl-es@6467 dfc29bdd-3216-0410-991c-e03cc46cb475

examples/25.XmlHandling/main.cpp

@@ -500,7 +500,7 @@ int main()
 			app.Gui->drawAll();
 			app.Driver->endScene();
 		}
-		app.Device->sleep(10);
+		app.Device->yield(); // be nice
 	}
 
 	//app destroys device in destructor