Release 4.8.0

[chyunsu3]

Pull requests

• Export more metadata from export_model() #684
• Exporter: export classes_ attribute for subestimator of RF #686
• Implement bulk import for IsolationForest #687

[chyunsu3]

Implementing #690 may take some time, and I don't want to hold up the new release too long. Let me prepare a new patch release instead.

[chyunsu3]

Some pull requests have now been moved to #691