Improve liquid craft container handling
Restyle vehicle_parts.json 3/4.
Restyle vehicles.json 3/4.
Restyle materials.json 2/3.
Restyle mutations.json 2/3.
Restyle species.json 2/2.
Merge branch 'master' into Crafting
Style oter_t.
Remove settlement.cpp as it is no longer used at all.
Move colour lookup to a map.
Completely replace the oter_id enum by new overmap_terrains.json.
Merge branch 'master' into Crafting
Improve liquid craft container handling WIP
Merge branch 'master' into buildings_json
Fix overmap terrain allow_road checks.
Style and comment overmap::make_hiway().
Improve container handling WIP
overmap: fix legacy save/load
load_overmap_terrain; pre-set is_river, is_road, and set "id_base" prior to _north, _sw, etc
oter_id: switch from std::string to struct { int _value; } with flexible translation methods
generate: optimize the frack out of it; temporary until over/under etc is jsonized
Merge branch 'master' into Crafting
Turn metal tank into a container.

Also changed volume to reflect holding capacity.