Require two blades for the blade trap because disarming gives you two blades back.

The items you get back upon disarming are defined in data/json/traps.json as "drops", for tr_engine it's
"drops" : ["motor", "blade", "blade", "string_36"]
Fix minor glitch in item info display in crafting screen.

The iteration starts with i = 1, thereby the first line of the item info (folded[0]) is not printend.
That line contains the volume and weight of the item.

The folding and printing is done with fold_and_print, starting at the second line.
Fix crash when toggling available constructions.
More consistency checking for terrain / furniture:

Check terrain/furniture that is used on close/open action.
Check terrain in ter_t::transforms_into.
The monster is identified as mon_zombie_fireman not mon_zombie_firefighter