Use dataclasses to better encapsulate large tuples and untyped dictionaries

[padix-key]

Currently, some places in biotite use excessively large tuples and dictionaries without strict typing as input or return values.
For the next major release these places should be refactored to make the API more readable and improve type checking.

[padix-key]

A similar approach could be made in GenBankFile: Here a GenBankRecord could clarify the 'items' a GenBankFile contains.