On the 'move-tracking-2' branch: Rename 'node-branch'/'nbid' to 'element'/
'nbid'.

(The term 'node-branch' had been used loosely, not necessarily implying a
particular branch.)

git-svn-id: https://svn.apache.org/repos/asf/subversion/branches/move-tracking-2@1636903 13f79535-47bb-0310-9956-ffa450edef68