[augeas-devel] Various XPath enhancements and fixes

[David Lutterkort]

This series of patches fixes and enhances the XPath expressions in the
following ways:

 * correctly match multiple predicates, so that /path[pred][last()]
   returns the last node from the nodeset /path[pred]
 * compare numbers for equality/inequality and less/greater than
 * add position() and count(expr) functions
 * add boolean operators 'and' and 'or'

As always, the file tests/xpath.tests contains a variety of examples of
what is possible now.