Change CURIE rel to 'curies'.
Make CURIEs always be an array.
Merge branch 'refs/heads/master' into draft4
Add deprecation link attribute.
Bump Internet draft version in README.
Work toward draft 3 back-compatibility.
Create documents with explicit draft version.
Extract draft detection.
Move more curie stuff to Draft.
Remove duplicate autodetection from Document.
Extract constants for "_links" and "_embedded".
Add some docstrings about drafts.
Test that empty documents default to latest draft.
Improve docs.
Update README.
Merge branch 'refs/heads/back-compatibility'
Bump version number.