Changed approach to merging Query::Path into Query
Changed approach to merging Query::Path into Query

* Now returns the relationships in the expected order, allowing
  join logic in the DO adapter to become simplified.
* Changed Query#links to be private.  :links option will also become
  private in the future because it does not map well to any other
  datastore, and new approaches will be needed to handle m:m
  associations.

datamapper/dm-do-adapter,basex/ardm-do-adapter