PN Invoice 0.2.0

Changed

• Breaking: the root namespace is now Pnscripts\Invoice\ (was PnScripts\Invoice\), the
  spelling every PN Scripts package uses. Behaviour is unchanged. To upgrade, replace
  PnScripts\Invoice\ with Pnscripts\Invoice\ in your use statements and type references,
  for example sed -i 's/PnScripts\\Invoice/Pnscripts\\Invoice/g' $(grep -rl 'PnScripts\\Invoice' src).
  Composer's autoloader matches the prefix case-sensitively, so the old spelling fails with
  "class not found" until it is updated.

PN Invoice 0.1.0

First release: EN 16931 invoice and credit note model, UBL 2.1 and CII D16B writers, layered validation (XML safety, bundled XSDs, 104 EN 16931 business rules in pure PHP, optional Schematron adapter), and a CLI. The business rules cover a documented subset of EN 16931; see README. Not legal or tax advice.