Code style: move or add licensing information on top of every file

AI/EmptyAI/CEmptyAI.cpp

@@ -1,3 +1,12 @@
+/*
+ * CEmptyAI.cpp, 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
+ *
+ */
 #include "StdInc.h"
 #include "CEmptyAI.h"
 

AI/EmptyAI/CEmptyAI.h

@@ -1,3 +1,12 @@
+/*
+ * CEmptyAI.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
 
 #include "../../lib/AI_Base.h"

AI/EmptyAI/exp_funcs.cpp

@@ -1,3 +1,12 @@
+/*
+ * exp_funcs.cpp, 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
+ *
+ */
 #include "StdInc.h"
 
 #include "CEmptyAI.h"
@@ -16,4 +25,4 @@ extern "C" DLL_EXPORT void GetAiName(char* name)
 extern "C" DLL_EXPORT void GetNewAI(std::shared_ptr<CGlobalAI> &out)
 {
 	out = std::make_shared<CEmptyAI>();
-}
+}