Added 'Serializeable' base class for classes serializeable by pointer

lib/serializer/Serializeable.h

@@ -0,0 +1,21 @@
+/*
+ * Serializeable.h, part of VCMI engine
+ *
+ * Authors: listed in file AUTHORS in main folder
+ *
+ * License: GNU General Public License v2.0 or later
+ * Full text of license available in license.txt file, in main folder
+ *
+ */
+#pragma once
+
+VCMI_LIB_NAMESPACE_BEGIN
+
+// Tag class that acts as base for all classes that can be serialized by pointer
+class Serializeable
+{
+public:
+    virtual ~Serializeable() = default;
+};
+
+VCMI_LIB_NAMESPACE_END