WIP: Class version

[dalonsoa]

This PR suggest some exploratory work implementing the same functionality (the readers in this case) using classes and subclasses.

The reason for this change is:

• Reduces some redundancy of the code, in particular when reading headers.
• Has a slightly better separation of concerns.
• Enables using the header to validate or do something else with the tabular data more easily in the future, implementing dedicated methods within each subclass.

No need to do a thorough review, just gathering some feedback on the approach, pros, cons and things to consider.

[AdrianDAlessandro]

I think this approach helps with keeping things consistent and not repeating code. There could be a more more functional way to do this, but I think this is maybe clearer than that would be.