Mustang 2.1.1 fixes
- recipient contacts in XRechnung
- remove outdated dependency
- allow XRechnung without street
- only deploy library and validator to maven central, not core nor cli
- a correction should reference the original invoice via invoiceReferencedDocument, not buyerOrderReferencedDocument
- upgraded CEN Schematron validation (codes 24) to v1.3.4
- added unit tests for ubl conversion and visualization
- and adds the possibility to specify a seller order referenced document