fix bug: when schema is imported from an imported schema, we must use the imported schema location instead of the wsdl location as the imported schema can be located elsewhere from the wsdl location.
fix bug: when schema is imported from an imported schema,
we must use the imported schema location instead of the wsdl location
as the imported schema can be located elsewhere from the wsdl location.

WsdlToPhp/PackageGenerator,WsdlToPhp/PackageGenerator