Load all files in data/json automatically.

Had to move some stuff to make this work.

`data/json/colors.json` ~> `data/raw/colors.json` (is not loaded by init.cpp)
`data/json/vehicles.json` ~> `data/json/vehicles/vehicles.json` (depends on vehicle_parts.json)
`data/json/halloween_special.json` ~> `data/recycling/halloween_special.json` (it's not halloween)
`data/json/items/instruments.json` ~> `data/recycling/instruments.json` (doesn't work)