Synchronized source file headers (#3212)

* Alphabetically sorted includes.
* Updated copyright and license text to match across all files.
* Removed pragma once define in header files in lieu of ifdef guards.

src/char/int_elemental.cpp

@@ -1,4 +1,4 @@
-// Copyright (c) Athena Dev Teams - Licensed under GNU GPL
+// Copyright (c) rAthena Dev Teams - Licensed under GNU GPL
 // For more information, see LICENCE in the main folder
 
 #include "int_elemental.hpp"
@@ -7,10 +7,10 @@
 #include <string.h>
 
 #include "../common/mmo.hpp"
-#include "../common/strlib.hpp"
 #include "../common/showmsg.hpp"
 #include "../common/socket.hpp"
 #include "../common/sql.hpp"
+#include "../common/strlib.hpp"
 
 #include "char.hpp"
 #include "inter.hpp"