JAXP interface (transformation, XPath, schema processing)

A new interface ActiveSource is introduced as a sub-interface of the JAXP Source interface. Unlike Source, this is a true interface in that Saxon will accept any class that implements the interface. An ActiveSource must implement the method deliver(Receiver receiver, ParseOptions options), which Saxon calls to obtain the contents of the source: the method must deliver a sequence of events to the supplied Receiver. The ParseOptions can be ignored if not required; they are relevant primarily in cases where the ActiveSource performs XML parsing.