code: public void addRoute(final LocalTrustGraphNode a, final LocalTrustGraphNode b) {
          addDirectedRoute(a,b);
          addDirectedRoute(b,a);
      }
docs: add bidirectioanl trust graph links between two nodes.
  
  @param a node that will form a trust link with 'b'
  @param b node that will form a trust link with 'a'