Experimental batch crafting time reduction
Remove redundant get_batch_time function
Remove redundant instances of difficulty property

Difficulty is now loaded only by the requirements class, and is
automatically shared with constructions and recipes.
Logistic function batch crafting time reduction

A recipe can now have optional `batch_time_factors` array which
specifies maximum time reduction for a single craft as a percentage,
and a minimum batch size to reach the full time reduction.
Use batch_time within make_all_craft
Example batch benefits for two food recieps
Update JSON_INFO with batch_time_factors explanation
Atomic coffee recipe tweak.

I'd never noticed this oversight before.
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
Fix bug, only check ter_t::transforms_into when it's needed.
Created Mundane_Zombies mod
Pickup: move creation of windows into the block that actually uses them.

Previously the windows would have been created on *every* move. The header would be printed, but the window would not be refreshed via wrefresh.
Only upon deletion it would appear on screen, but immediately overdrawn by the sidebar.
Merge branch 'batch-crafting-benefits' of https://github.com/drbig/Cataclysm-DDA into merge
Merge branch 'mixed-bugfixes' of https://github.com/BevapDin/Cataclysm-DDA into merge
Merge branch 'recipe-tweak' of https://github.com/Rivet-the-Zombie/Cataclysm-DDA into merge
Merge branch 'mundane_zombies' of https://github.com/daftfad/Cataclysm-DDA into merge