Implemented sell, not validate sell
merge fix
Fixed some errors. Added some changes to the DisplayUniverse controller.
Merge branch 'master' of https://github.com/gem-5/last-adventures
Properly merged.
Merged the change of Ship.getCargoCount from Good to GoodType
fixed double import of util.Map
Buying and Selling goods works as needed for demo. Currently, planet's stock will be redetermined each time you buy or sell a product.
Prints error message in the GUI instead of in console @market