Make opennwa::NestedWord into a wali::Printable
Add a 'operator<<(ostream, NestedWord)' function
WFA::intersect needs to initialize the query direction in dest

Otherwise doing intersect() then path_summary() would extend in the
wrong direction half the time. I do the same thing as the original
intersect version: dest.query = this->query.
Set my intersect() as default; introduce intersect_cross()
Now that my intersect works (I think), use it in XFA