Change internal data layer and output clusters as GenBank files

Added

• Export of cluster sequences with genes and domain annotations in GenBank format.
• Proper data model to allow retaining more information from input.
• Dedicated functions to load the KNN training matrix and the CRF model.

Fixed

• Sorting issue causing ClusterCRF to be passed a feature table with potentially scrambled proteins.

Changed

• All internal classes but ClusterCRF expect objects from gecco.model instead of pandas.DataFrame.
• KNN training matrix is now stored as a compressed sparse matrix.
• Internal data is stored in the relevant module next to the code needing it instead of in a dedicated gecco.data module.
• gecco.orf.ORFFinder works at the single record level.
• Reduce code complexity in gecco.hmmer.DomainRow and gecco.refiner.ClusterRefiner.

Removed

• Export of individual cluster proteins in FASTA files.
• Unused ProdigalFinder (since PyrodigalFinder is used instead).