Now no longer using a subclass of AssociationReflection - we weren't using anything within the class anymore anyway. So, that's good. Supporting three different approaches for generating associations isn't quite so fun though.
This resolves the insistent warning about errors in transactions, covered in #867.
The :path option - if not nil - should be the full path to the folder you want the files for this index to be located in. ThinkingSphinx::Index.define :book, :with => :active_record, :path => Rails.root.join('sphinx/custom') do Nested directories specified will be created as needed.