node attributes

render="false"

calling get_content for a node which is render=false does:

o if it has children or younger siblings, you get the first of those

o if it has neither of those, you get the node's content
  (aside:  the current client just fails here)

When encountered inline (as in viewing a render=false node's parent), the node is just pruned.

Aside: in the java client, accessing any terminal node which is r=f is an error