Deserialize

This PR includes:
- Refactoring of JSON-related methods in all classes (had a lot of redundancy in the code)
- Cleaning of the main
--> Loading content from a JSON file.
- Took out all `UDeviceSummary*` from the project (but did not delete files yet). I believe those classes are pointless. We can generate (and load, vice versa) a JSON in a summary format without having a different class.