Fix documentation and behavior for 1.13 release

src/main.c

@@ -102,7 +102,7 @@ int main(int argc, char **argv) {
   }
   lua_setglobal(L, "ARGS");
 
-  lua_pushstring(L, "1.11");
+  lua_pushstring(L, "1.13");
   lua_setglobal(L, "VERSION");
 
   lua_pushstring(L, SDL_GetPlatform());