Split spec

Hi folks,

It was way more difficult than you'd think it ought to have been, but
I have divided the XProc specification into two separate documents.

The language spec:

  https://ndw.github.io/specification/langspec/split-spec/head/xproc20/

And the standard step library:

  https://ndw.github.io/specification/langspec/split-spec/head/xproc20-steps/

I took the liberty of integrating p:template and p:in-scope-namespaces
into the standard library. (This makes the namespace document more
complete, if nothing else.)

In an effort to do the minimum necessary to the prose, I've arranged
things so that cross document links work just like the used to.
Visually, I added a little superscript annotation to the
cross-document links. It could probably do with being made more subtle
if we like it.

Yes, the Introduction to the standard step library is just an
ellipsis. :-)

If we like the divided spec, we're going to want to think about the
editorial issues a little but along the way. Should, for example, some
of the glossary terms be repeated in each spec instead of
cross-referenced.

Comments, please.

                                        Be seeing you,
                                          norm

-- 
Norman Walsh
Lead Engineer
MarkLogic Corporation
Phone: +1 512 761 6676
www.marklogic.com