Updating imports.

enstools/encoding/api.py

-from .definitions import Compressors, CompressionModes, compressor_aliases, compression_mode_aliases
-from .encodings import FilterEncodingForXarray, FilterEncodingForH5py
-from .compressors.availability_checks import check_dataset_filters_availability, check_filters_availability, \
-    check_sz_availability, check_zfp_availability, check_blosc_availability, check_libpressio_availability
\ No newline at end of file
+from .definitions import lossy_compressors, lossy_compression_modes, lossy_compressors_and_modes, lossless_backends
+from .variable_encoding import VariableEncoding, LossyEncoding, LosslessEncoding, NullEncoding
+from .dataset_encoding import DatasetEncoding