improved xml matching - so far only element nodes (with its attributes) were considered - now also consider TEXT, CDATA, and COMMENT nodes - added function text_matches (normalizing consecutive whitespace to a single space)
improved xml matching
- so far only element nodes (with its attributes) were considered
- now also consider TEXT, CDATA, and COMMENT nodes
- added function text_matches (normalizing consecutive whitespace to a single space)

added some new unit tests
- test_consider_non_elements:
  non-element nodes are not yet considered in <if> and <macro>

ros/xacro,ros/xacro