Test whether a DaatsetRef is read-only.

git-svn-id: https://svn.apache.org/repos/asf/jena/trunk@1446074 13f79535-47bb-0310-9956-ffa450edef68
Pull up ver.xerces, pull up build timestamp, in to jena-parent

git-svn-id: https://svn.apache.org/repos/asf/jena/trunk@1446079 13f79535-47bb-0310-9956-ffa450edef68