Disease.cpp fixes
Tweaked pain due to heat
Lowered homeostasis adjustement while hot
Rewrite armor damage absorption code
Rewrite armour damage code
Added chitin as a material
set up JSON for materials
Added more materials calls, moved material resistance matrix to json
use materials functions in armour absorption code
Fixed material not being passed correctly, and added chitin to item factory
separate out materials contributions to armour protection values
outer layers of armour protect inner layers
Rework learning mechanics, following issue #613

Implements items 1 through 5, from issue #613.
Fully separate armour geometry from materials
Added American Flag Spawn for School
Added American Flag
Added GET_FLAG
Added Find Flag
Added find flag dialogue
Added Cathedral