new bookmarklets

Hi all,

I've updated the RDFa javascript bookmarklets to abide by the new rules
we've defined regarding striping, @resource, the non-use of @id, etc...
I've also added the correct typing of literals (which was missing), and
the rules agreed upon for default datatypes.

I have *not* frozen this code with a timestamped URL, because I'm sure
it's quite buggy and needs some testing before anyone comes to rely on
it for anything.

Please test it out! In particular, use the GetN3 bookmarklet to check
that the right triples are produced on various examples.

Here's the bookmarklet page:

http://www.w3.org/2006/07/SWD/RDFa/impl/js/

-Ben