Code review comment for lp:~widelands-dev/widelands/tutorial-improvements

If the player destroys the quarry construction site, he is not allowed to rebuild it. I see three possibilities:

- Allow the user to rebuild the quarry. This would mean to redefinitions of immovable_is_legal() inside the while loop, which makes the code quite messy.
- Send a message to the user that destroying the quarry was not clever, and ask him to restart from savegame xy. However, this makes the impression that we were lazy.
- Leave it as is. The unexperienced user will hopefully not dismantle the quarry. If he does, the game does not crash. I can also remove the inner while loop, so the player gets automatically notified that something went wrong.