Add more analysis tools

[alecandido]

Looking into Pylint I discover they also ship a script called symilar, to check for copy-pasted code.

I hope this will never detect anything, but since many people are working on these projects I have a preference for more automated tests (and being shipped by Pylint I consider it reliable and maintained, and we would not need any further dep).

Moreover, I'd like to introduce mypy checks as well, even if as a first step I would make failures opt-in.
Type hints are optional, but also incremental, so mypy will try to infer as much as possible, and more we'll use consistent types and type hints (as it is happening with dataclass, that make them mandatory) more useful mypy checks will be.

[alecandido]

@scarrazza even here I'd like to have your opinion, please :)