Deprecate and remove _editAsPickList

(Bug, To be Fixed , Priority: High, Test Status: No automated tests yet , Reported By Justin du Coeur, )
Functions
Summary: Now that we have _checkList(), this can go away.
This also lets me remove the client-side PickLists code, and the HtmlRenderer's PickList-rendering code.
Does this also let me remove the whole RenderSpecialization pipeline? That would be nice...