swars: Enable domes being passable when opened

This was prevented due to two bugs in the game code.
Original levels were adjusted for this bug, so an update
to Zealot campaign was required to make it work properly.

Now as levels are updated to mind the domes, this patch
enables the code fix which makes entering domes possible.

src/thing.c

@@ -868,10 +868,8 @@ ThingIdx new_thing_building_clone(struct Thing *p_clthing, struct M33 *p_clmat,
         p_thing->U.UObject.PrevThing = p_clthing->U.UObject.PrevThing;
         p_thing->U.UObject.OffX = p_clthing->U.UObject.OffX;
         p_thing->U.UObject.OffZ = p_clthing->U.UObject.OffZ;
-#if 0 // Disabled until the domes entering is considered safe to enable
         p_thing->U.UObject.BuildStartVect = p_clthing->U.UObject.BuildStartVect;
         p_thing->U.UObject.BuildNumbVect = p_clthing->U.UObject.BuildNumbVect;
-#endif
         // Copy all fields from Turn down
         p_thing->U.UObject.Turn = p_clthing->U.UObject.Turn;
         p_thing->U.UObject.TurnPadOnPS = p_clthing->U.UObject.TurnPadOnPS;