Panthro Versions Save

• Minor project modernizations for building on macOS 10.12 Sierra.

• The intersect, except, and union operators from XPath 2.0 are included to go along with the XPath 1.0 | operator. All of these "set" operators are fully functional when operating on node-sets (other types of sequences are not available in XPath 1.0 or Panthro).

• Better display of the current context node while debugging an XPath expression step-by-step.
• The string values of Attribute and Namespace nodes are no longer erroneously reported as separate Text nodes.

Pretty complete/stable now. Close to 1.0.