[half-heights] Concrete tube tunnel crashes the game.

[Rollmaterial]

After building a concrete tube tunnel, going into underground mode crashes the game.

[jamespetts]

I think that I have fixed this; would you be able to re-test?

[Rollmaterial]

From the commit descriptions I assume it requires recompiling makeobj, am I right?

[jamespetts]

No, just recompiling the Simutrans-Experimental executable should suffice.