Make it easier to combine two or more SourceCollection and TechnologyCollection objects #235
Description
During the work on the prototype of the new technology-data, it emerged the necessity to introduce SourceCollection and TechnologyCollection objects, which are currently Lists of respectively Source and Technology objects.
This issue advocates for the overriding of the __add__() method for both SourceCollection and TechnologyCollection, so that the combination of two ornmore SourceCollection objects (or two or more TechnologyCollection objects) becomes easier.
Furthermore, the current implementation of the prototype sees SourceCollection and TechnologyCollection as lists. Lists however support duplicates, which do not really make sense in this case.
Therefore, SourceCollection and TechnologyCollection should be turned to set.