Currently, a lot of functionality for the different Reader and Writer is based on <File> and thus quite restricted.
Rework the Reader and Writer structs for all modules to be more generic, e.g. require Read + Seek etc.

This would enable clients to be more dynamic in input and output data. For example, one could use an S3-based reference genome and ATGlib would only read the required sections, not have to download the full reference genome. It would also allow streaming from/to S3. (use https://crates.io/crates/s3reader)