Code review comment for lp://staging/~widelands-dev/widelands/new-tutorials

I found one bug:

- secret_village.lua:17 attempt to call global send_msg, a nil value.

I fixed it in 7251.

I didn't look over all the code as Gun did that already. What I saw looked good (local variables by default mainly and consistent style). The campaigns and tutorials are a lot of fun to play, I really enjoyed this. Thanks for your work on the campaigns - should you want to do more, just ask :).