Modeling trade

[jdebacker]

One approach to modeling trade flows with differentiated production goods may be that illustrated in Ballard et al. (1985), Chapter 3 (see Section 3.7 beginning on page 45).

I've started outline how this would work in OG-Core in the model_trade_flows branch in my fork. The changes thus far are contained in a new chapter on trade.

[jdebacker]

Source for product level trade elasticities: https://www.cepii.fr/cepii/en/bdd_modele/bdd_modele.asp