Import pugixml-1.7 as textproc/pugixml.

pugixml is a light-weight C++ XML processing library. It features:

* DOM-like interface with rich traversal/modification capabilities
* Extremely fast non-validating XML parser which constructs the DOM
  tree from an XML file/buffer
* XPath 1.0 implementation for complex data-driven tree queries
* Full Unicode support with Unicode interface variants and automatic
  encoding conversions

The library is extremely portable and easy to integrate and use.

(wiz)