Plugin core

- Code of SLOCCount plugin (https://github.com/jenkinsci/sloccount-plugin) heavily reused as a base code.
- Parsing of TODOs XML format implemented.
- Eclipse formatting defined.
- TODOs icons added.
- Plugin is compilable, but it is not runnable at all at the moment.
Parsing of input XML report

- All issues related to parsing of input XML report should be solved now.
- XSD schema moved to a proper location.
- Version attribute of report can't be transient, JAXB fails in such case.
- Logger is passed to the parser, warning and info messages can be put to build log.
- Workaround to fix failing tests during mvn package found, it is part of pom.xml and Makefile but commented out.
- Javadoc comments updated and extended.