Added support for XSD validated XML config files

- BIG refactoring included
- more docs
- some tests
- some examples that may be outdated now
- writing of JSON/XML/PHP settings
- first step for release of new version
- too many things to mention (sorry) :)

This should be a rather usable version now. It can read XML/JSON/PHP
config files and output a report to the CLI and write settings emitted by
the processed checks as XML/JSON/PHP files (for apps to include/use).