tree 1becf1b8b9a5b4650c6325789b8df2873a4a6b8d
parent b2a8c1fcc2e1ba23a1ab52c863985e7a05254dd5
author Jonathan Hart <jono@onlab.us> 1398926649 -0700
committer Gerrit Code Review <gerrit2@gerrit.onos.onlab.us> 1399477699 -0700

Break the references between Port and Link.

This is in preparation for implementing topology versioning. Ports may have
different Links in different versions of the topology, so we don't want the
reference inside the Port object. References are now held in indexes in the
NetworkGraphImpl.

As a result of this, there was a small API change:
  NetworkGraph.getLink  ->  NetworkGraph.getOutgoingLink
  NetworkGraph.getIncomingLink was added.

Change-Id: I086d198c8040607253c8729b9d5f94ab6bc738db