eep3: rdfn3.g

Since people have been asking for it, and it's basically done: here's my
updated rdfn3.g, plus associated Python and XHTML files. It fixes a number
of bugs (such as variable name clashes, preprocessing comments), cleans up
the grammar in general, and is now API independent.

Bugs:-

* Yapps doesn't process comments properly, so I had to write a small
pre-processor.
* For some reason, it won't recognize the optional period at the end of
formulae, so it's basically forbidden.

These appear to be problems with Yapps, so I might ping the author about
it.

--
Kindest Regards,
Sean B. Palmer
@prefix : <http://purl.org/net/swn#> .
:Sean :homepage <http://purl.org/net/sbp/> .