New PriceFetchrequest.loadDataFromNetwork() that can fetch price data from MKM
Removing data when changing the price engine
Removing data when changing the price engine 2 : the return

I added the price engine in the cachekey. It was <name>-<set>, therefore when the priceengine was changed, for the existing cards the price was fetched from the cache instead of the network. The way the price engine is part of the cache key could be improved though.