-Added AnimationGraphPlayer (still missing features)

-Added ability to edit resources from built-in inspector (wip, needs testing and feedback)

scene/scene_string_names.cpp

@@ -187,6 +187,8 @@ SceneStringNames::SceneStringNames() {
 
 	node_configuration_warning_changed = StaticCString::create("node_configuration_warning_changed");
 
+	output = StaticCString::create("output");
+
 	path_pp = NodePath("..");
 
 	_default = StaticCString::create("default");