Merge pull request #524 from Goober5000/small_fixes

one small bugfix, one small comment tweak

Author: MageKing17

code/hud/hudlock.cpp

@@ -253,9 +253,9 @@ void HudGaugeLock::render(float frametime)
 		}
 	}
 
+	// show locked indicator
 	Lock_gauge.sx = sx - Lock_gauge_half_w;
 	Lock_gauge.sy = sy - Lock_gauge_half_h;
-
 	if (Player_ai->current_target_is_locked) {
 		hud_anim_render(&Lock_gauge, 0.0f, 1);
 	} else {

code/model/modelread.cpp

@@ -352,6 +352,10 @@ void model_instance_free_all()
 		}
 	}
 
+	// clear skybox model instance if we have one; it is not an object and therefore has no <object>_delete function which would remove the instance
+	extern int Nmodel_instance_num;
+	Nmodel_instance_num = -1;
+
 	Polygon_model_instances.clear();
 }