Imps walk through walls

[meldrian]

When the player marks some for the imps inaccessible earth/rock tiles for excavation, the imps can not reach them and do nothing.
However, if the player connects those inaccessible tiles by mark another, this time accessible tile in front of them for excavation too, the imps ignore that the accessible tile is still present and blocking the way, walk through it and begin to dig the former inaccessible walls behind it.

[Varkalandar]

Ah yes. I actually know the reason for this, but no solution yet. I'll fix it once I have a good idea hiw to circumvent the problem that made me allow the imps to move through marked-for-excavation tiles if the are doing path finding to mine yet another marked tile.