Digging invaders: improved edge cost evaluation.
Digging invaders: fixed a few problems involving digging and stairs, added a way to debug path cost, added a way to set the cost of each type of invasion job, made invaders only pathfind to one local instead of all of them.
Digging invaders: buildings can only be destroyed orthogonally, made path cost deal with hatches and raised bridges, but did NOT yet make job assignment deal with them.