Split mapping

[LadyChristina]

All Submissions:

• [x] Have you followed the guidelines in our Contributing documentation?
• [x] Have you verified that there aren't any other open Pull Requests for the same update/change?
• [x] Does the Pull Request pass all tests?

Description

Split "mapping" into two modules, mapping and aggregation. Now the mapping is only responsible for mapping blocks to entities (and is not dependent on any timeframe), while the aggregator generates the files with information about the distribution of resources to entities for some timeframe.

Also replaced file reading / writing method (json and csv methods instead of simple string parsing) for clarity and easier testing / maintenance.

Left to do:

• [x] Add content to mapping tests
• [x] Update documentation