[test] Add tests for pom paths specification

Note: it tests features that are not implemented/broken at the moment.
[macros] pass -r (recursive) and -f (force) options to pom_editor

Options added only to macros where it makes sense.
[test] add tests for recursive mode and force option
[pom_editor] implement recursive mode and force option
[test] refactor tests
[test] tests for pom_change_dep and other artifact macros
[pom_editor] implement pom_change_dep
[pom_editor] don't follow module nodes where arbitrary content is
allowed
[pom_editor] replacement coments identify what has been removed
[pom_editor] pom_xpath_* can manipulate arbitrary XML files
[pom_editor] Implement dependency handling macros for Ivy
[pom_editor] allow removing pars with pom_change_dep
[pom_editor] tests for generic xml files and ivy files
[pom_editor] Use namespace prefixes from input file
Add parser for new XMvn metdata generated by pyxbgen

Command used to generate it:
$ pyxbgen -u xmvn-core/target/generated-site/resources/xsd/metadata-2.0.0.xsd \
    -m metadata

This needs xsd file to be built by modello first
[test] Add metadata in new format for depmap_test
[test] Point to the right directory
[test] Remove tests for "old" depmaps
[test] Fix metadata for depmap tests
[man] Document new features in pom_editor