Made changelog current as of b836cdc78ef97ee9688030a1f152192f8140e93e.
A number of copyedits and fixed some ommisisions.  Thanks all.
Batch time reduction for boiling, broth, and soups
Batch time reduction for meat recipes
Meat jerky batch time'
Fix human bologna time
Whoops, batch scaling on wrong line
Vehicles block acid fields
Removes muzzle gunmod location on revolvers
Create constants for bounds of scentmap in for loops.
Whitespace formatting for grscent assignment readability.
Rename bool matrix has_wall_here to blocks_scent.
Rename bool matrix reduce_scent_here to reduces_scent.
No need to compare bools to bools.
Additional comments and some rewording.
Pre-increment instead of post. Bleh.
Basic curing and tanning.

Hides/pelts are now perishable (and if you're desperate, edible) and
requiring curing to keep from spoiling. Cured hides can be tanned; this
process takes about two days to complete, after which they can be
activated to turn them into a single large piece of leather or fur.
Recipe integration.
Modern tanning recipes and book.

New book is found in textbooks, gun xtras, and camping item_groups.
Flag derp.