Import combined Enhanced viewport: zoom out, overlays & tooltips (r53_27127) patch

https://www.tt-forums.net/viewtopic.php?f=33&t=53394

src/plans.cpp

@@ -0,0 +1,21 @@
+/* $Id$ */
+
+/*
+ * This file is part of OpenTTD.
+ * OpenTTD is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, version 2.
+ * OpenTTD is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+ * See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with OpenTTD. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+/** @file plans.cpp Handling of plans. */
+
+#include "stdafx.h"
+#include "plans_base.h"
+#include "core/pool_func.hpp"
+
+/** Initialize the plan-pool */
+PlanPool _plan_pool("Plan");
+INSTANTIATE_POOL_METHODS(Plan)
+
+Plan *_current_plan = NULL;
+Plan *_new_plan = NULL;