Planks on map tiles can now be used to cover pits and spiked pits

Player no longer has to have a 2x4 in the inventory to cover a pit or spiked pit with it.  The new function now checks for 2x4s in a 1-tile radius around the player and offers the option to use that instead.

One iffy part is if the plank is in the pit tile, I'm assuming the plank is leaning against the side of the pit nearest the player and can be hauled up, as opposed to the plank completely lying at the base of the pit and inaccessible.