Code cleaning, better documentation and updated CI.

enstools/encoding/api.py

+"""
+Application Programming Interface
+
+Access point to have access to all utilities defined in enstools-encoding
+"""
+
+# pylint: disable= unused-import
 from .definitions import lossy_compressors, lossy_compression_modes, lossy_compressors_and_modes, lossless_backends
 from .variable_encoding import VariableEncoding, LossyEncoding, LosslessEncoding, NullEncoding, Encoding
 from .dataset_encoding import DatasetEncoding