Lined up DataSet params with the documented fields. Documented extra param. Fixed .sanitize() to replace with None (the old code no longer did quite what was documented).
Lined up DataSet params with the documented fields. Documented extra param. Fixed .sanitize() to replace with None (the old code no longer did quite what was documented).

hobson/aima,hobson/aima,hobson/aima,ttalviste/aima,ttalviste/aima