colan's sandbox: Ancestry

At the moment, this module does not provide any UI-facing functionality, but provides the tools necessary for other modules to take advantage of hierarchical data set properties (lineage/ancestry information).

For now, the primary use of this module is to provide a recursive function that returns the lineage information of a given entity so that components such as breadcrumbs and tokens can put together a full path.

There will be plumbing provided to allow for various relationship types, but initially, only Entity reference will be supported.

Essentilally, this is a hack until something like Tree is fully baked.