A price adjustment procedure to find equilibrium prices for differentiated
commodity markets.

Finds a minimal Walrasian equilibrium using the procedure of generalized
English auction (Gul & Stacchetti 2000). Export flows are constrained by
capacity in `supply` and are differentiated by floor prices for market entry
in `markets` :entry. The individual market demand in `markets` :demand is
assumed to be inelastic. Import goods can be substituted with domestic
production at higher market prices. International suppliers and domestic
industry players alter their supply volumes identically in response to the
changes in market price. `price-scale` is an upper bound on market price
corresponding to the case of only domestic supply. Returns a hash map with
supplier prices (:suppliers) and market prices (:markets) for each auction
iteration.