v0.4.0

Full Changelog

Merged pull requests:

• refactor: remove Feature::Base, just use Feature::Permissions #13 (lanej)
• refactor: collapse some hierarchies, model operations as functions #12 (lanej)
• fix: handle abbreviations and numbers in feature name #11 (lanej)
• Deprecate constant lookups via .const_missing #10 (lanej)