JAXP interface (transformation, XPath, schema processing)

The classes ProfessionalXPathFactory and EnterpriseXPathFactory are dropped. It seems there were no tests referencing these classes, and JAXP XPath has gradually been deprecated.

The zero-argument newSchema() method of the JAXP SchemaFactory class now returns an empty schema (one containing only the built-in components such as xs:integer). This conforms more closely to the JAXP specification. Previously the method returned the global schema for the Saxon Configuration.