Couple multiple satellite models with the market model

@S.J.vanRijn I have connected 3 satellite models to the central model. The central model first combines demand bids from all satellite models and then clears the market. For now, the same (combined) market clearing result is sent to all satellite models. The next step will be to disaggregate the market clearing result and extract the specific demand met for each satellite model as described in this issue #11. Closes #5 (closed)