Tunneler party won't 'head for' Dungeon

[Loobinex]

The ADD_TUNNELLER_PARTY_TO_LEVEL script command has the [head for] parameter that allows you to configure to what the party will tunnel. When you use the 'DUNGEON' parameter in the level script, the party will tunnel in a random direction instead.

To reproduce:

1. Start level 18 of the original campaign
2. Wall yourself in, then mine all the gold in the south-west to trigger the parties. Frameskip for brevity.
3. Watch as the tunneler parties will go in any direction, sometimes even dig out the hero fortress in the north.

To see the difference in behavior, replace all the 'DUNGEON' parameters with 'DUNGEON_HEART' and see the parties will now consistently dig south.

Expected behavior of the parameters:

ACTION_POINT - Dig straight for the specified action point
DUNGEON - Dig straight for owned floor/rooms of specified player closest to the tunneler
DUNGEON_HEART - Dig straight for the specified dungeon hearth
APPROPIATE_DUNGEON - Dig straight for owned floor/rooms of player with the highest score closest to the tunneler