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

Thanks for all that proofreading and the other fixes. I will have a closer look at them later.

Economy, _try_add_objective: That was the name used in the former tutorial. It should now be replaced by add_campaign_objective. I did find&replace, but did not replay the whole tutorial afterwards.

1) Can I still do that after I have bzr rm it (I am not so familiar with bazaar)

2) Based on the code, this should happen here (line 240 in r7235):
while #plr:get_buildings("quarry") < 2 do sleep(1400) end
o.done = true

3) I will investigate when I have time. But that cs should refer to the first construction site.

Had the check "if panel ~= nil then" a special reason or was it just foresightful?