AT weapons not firing at engineering vehicles

I was testing svn rev 1856 but I think I noticed this a few revisions ago but forgot to report it.

Confirmed in current SVN version.

Appears all Armour-Piercing weapons are not targeting trucks, engineering vehicles, etc etc, even when given forced fire orders. They do however still fire at armoured targets normally.

Fixed hopefully. Stuka is a questionable case though: should it shoot at trucks too or would that be a waste of ammo?