Merge to mainline

Conflicts:
	src/disease.cpp
	src/game.cpp
	src/player.cpp
Power station item spawn redo.
Small documentation cleanup
Another small documentation change
More small documentation cleanups
data/json/items/mods.json: Several fixes
Rebalanced skill_required and fixed the weird indentation.
Line fix
Tileset credit uptate
Merge pull request #10082 from Mshock777/credits

Tileset credit update
Adds new tree, bark tanning leather option.

Adds the blackjack oak (Quercus marilandica) tree to forests.
Adds new item: tanbark, bark from a tree used in tanning leather. Can
sometimes spawn on the ground in forests or when blackjack oak is
examined.
Integrates new item into extant basic tanning recipe, and tweaks
quantity of acorns to respect new item.
A few material fixes.

Apparently carpet was made of steel?
change the spawn numbers of utility buildings
Merge branch 'power-stations' of https://github.com/John-Candlebury/Cataclysm-DDA into merge3
Merge branch 'spawn-lists' of https://github.com/Mshock777/Cataclysm-DDA into merge3
Merge branch 'hallucinations' of https://github.com/BevapDin/Cataclysm-DDA into merge3
Merge branch 'fix-ol-monster-world-bug' of https://github.com/BevapDin/Cataclysm-DDA into merge3
Merge branch 'container-prices' of https://github.com/Rivet-the-Zombie/Cataclysm-DDA into merge3
Merge branch 'foldable_vehicles' of https://github.com/jokermatt999/Cataclysm-DDA into merge3
Merge branch 'autobutcher' of https://github.com/Coolthulhu/Cataclysm-DDA into merge3
Reorder confidence and steadiness meter calculations.