hudmol/archivesspace — pull request #769 by marktriggs (2014-05-02 00:33:42+00:00)
Title: Accession to accession relationships

Add two new types of relationships between accessions:

* has_part/part_of -- basically, parent/child relationships
* bound_with -- a sibling relationship

To make this work I generalised the existing "directional" relationships code used by related_agents, and pulled that into its own mixin.

Pretty big commit, so happy to walk through over Skype for review.