Codechange: Let the compile generate the master command table out of templated command traits.

This is using a non-intrusive type-traits like templated system, which
allows compile-time validation that the command table and the command
enum match up.

src/story.cpp

@@ -25,6 +25,7 @@
 #include "game/game.hpp"
 #include "script/api/script_story_page.hpp"
 #include "script/api/script_event_types.hpp"
+#include "story_cmd.h"
 
 #include "safeguards.h"