ph-regep 3.0.0

• Moved XSDs into folder external/...
• Deprecated classes ERegRep4XMLDocumentType, RegRep4Reader and RegRep4Writer
• Added new package com.helger.regrep.jaxb with all the specific marshallers

Full Changelog: ph-regrep-2.0.0...ph-regrep-3.0.0