Misc: Use override and final C++11 keywords in a few places (mostly scripts)

OVERRIDE and FINAL are TC macros (expand to nothing if compiler does not  support C++11)

src/server/scripts/Examples/example_commandscript.cpp

@@ -43,7 +43,7 @@ class example_commandscript : public CommandScript
             return true;
         }
 
-        ChatCommand* GetCommands() const
+        ChatCommand* GetCommands() const OVERRIDE
         {
             static ChatCommand HelloWorldCommandTable[] =
             {