Added "overlay" functionality for player/NPCs.

New tileset IDs:
- overlay_worn_{ITEM ID}, overlay drawn over the character when the item is worn
- overlay_wielded_{ITEM ID}, overlay drawn over the character when the item is wielded
Removed superfluous null-check for worn items.
Fix draw_entity_with_overlays return type.

Function doesn't return anything.
Replaced item.type->id with item.typeId() in player::get_overlay_ids()
fixed scrolling in keybinding window
When loading active items, increment the active_item_count.
Remove outdated comment.
blockhead tileset: add missing entry for 't_concrete'
Blockhead tileset: add missing 'bg' to 't_concrete' and fix whitespace
Canvas bags and sacks, and crafting them.
Commercial fertilizer (solid) coming in canvas sacks as opposed to plastic bags.
Italian seasoning, black pepper, and seasoned salt coming in canvas bags.
SAI posts and fungicide in plastic bags
MShock's v0.27

nachosc
nachosm
nachosmc
datura_seed
seed_hops
seed_barley
seed_sugar_beet
seed_cotton_boll
bolt_metal
new mask_bal
tweaked snowflake
gave irradiated wanderer orange jumpsuit
fixed switchgear, supports
fixed seed_tomato
Guard rearmed

I am surprised no one tried putting rifle in the holster.
reduce the number of lemons needed because 2 lemons are hard to find, only one lemon is needed in reality, and requiring 2 lemons makes their use as a component much less meaningful
add other foods known to be useful for batteries
Water desalination recipe.

Simple boil-off method.
Byproducts tag fix.
Merge pull request #9055 from Mshock777/tileset-my

MShock's v0.27