BUY and SELL
	commodity id	} indexed	} indexed	} unique
	island id ??	}				} indexed?
	stall id					}
	=>?
	price		integer
	qty		integer, 1001 means `>1000'

COMMODITIES
	commodity id
	=>
	commodity name
	unit mass
	unit volume

ISLANDS
	island id
	=>
	island name
	archipelago name

STALLS
	stall id
	=>
	island id
	stall name

UPLOADS
	island id
    =>?
	age		integer time_t
	clientspec	us-ascii
	serverspec	us-ascii

DISTANCES
	island a id
	island b id
	distance	integer leagues