TODO
 * move context/input into property of the token
 * change context info (positions/count) into a stack on the context object, for nested predicates
 * implement the missing functions
 * tests for all functions ops
 * increase test coverage (currently 78.4%)
 * remove all the Data::Dumper use's

0.21 - 2009-04-10
 * added basic docs for main module
 * more tests
 * made it work correctly with the newer  XML-Parser-Lite-Tree syntax

0.20 - 2008-08-13
 * moved to string types
 * fixed attribute axis
 * enabled all zvon tests
 * started on function tests

0.19 - 2006-03-26
 * cleanup
 * code coverage
 * split out axis parser

0.18
 * more eval engine work - 1-22
 * function map
 * arg validation
 * axis handlers

0.17
 * more eval engine work - 7,8,9
 * function arg validation

0.16
 * more eval engine work - 6 and some of 7
 * ret type coersion

0.15
 * more eval engine work
 * zvon examples 3,4,5 and some of 6

0.14
 * started on the eval engine
 * zvon examples 1 and 2 eval correctly (t/05_zvon0[12].t)

0.12
 * tree builder can tree all zvon examples correctly (t/04_tree2.t)

0.11
 * tree builder started

0.10
 * tokener finished

0.02 - 2005-05-06
 * first CPAN release

0.01
 * first checkpoint