Rework configuration storage
Right now it's an ini file, without any hierarchy.
It's kind of a mess and could need some rework.
We could use JSON or YAML to store the new configuration (YAML allows comments so it's a better idea)
However, we also need to review :
- How the variables are called
- Where they're used in the code to rename them
- How to make them into proper objects with a hierarchy that makes sense
- Work with @Ziassan to see how to send them correctly from the frontend to the backend so it can be saved to disk.