Open issue: version declaration

See:

  https://github.com/invisibleXML/ixml/issues/63

I think we should adopt this proposal. It will give ixml grammars an
(optional) “magic number” so they are self identifying, and our future
selves will thank us for giving them a way to distinguish future
versions of ixml from 1.0.

                                        Be seeing you,
                                          norm

--
Norm Tovey-Walsh
Saxonica