CSL 1.0-b1

This is nothing official (as in no release on SF), but I’d be fine with
calling the existing state of the schema a decent 1.0-b1 version. I
just need to clean up the styles a bit more.

So I have formalized this by folding csl-alt.rnc into csl.rnc.

Let me know if you find any problems of course. I have no doubt there
are some little issues left.

I have not yet updated citeproc-xsl to use the new styles, though it
should be hard. Would certainly make testing the styles themselves
easier, since one has to imagine what the output should be!