added trig serializer
Another attempt at fixing literal equality, hash and comparison handling.
Here lexical representations and values are kept separately, but all comparisons happen in value space.

This is keeping the existing rdflib behaviour for literal > < comparisons, here everything is compared based on the value. This means we can do some neat things:

* Compare literals with python objects, i.e. Literal(1)<2
* Compare literals without regard to datatype: Literal(1)<Literal(2.0)

BUT

This means we more completely ignore http://www.w3.org/TR/rdf-concepts/#section-Literal-Equality
Which is quite clear that data-type and lang must match for equality.

Now, to make __eq__, __gt__ and __hash__ consistent this must be true:

>>> Literal('1', datatype=XSD.integer) == Literal('1.0', datatype=XSD.float)
True

Which is probably not what we want.

I belive the neat comparisons will have to go...
fixed sleepycat namespaces not being URIRef. fixes #201.
Check and rewrite namespace prefixes starting with _ in turtle serializer. fixes #161
Add toPython() methods to URIRef, BNode, Statement, Graph and Seq. Fixes issue #174
Merge branch 'master' of github.com:RDFLib/rdflib
Fix test failures (Hurrah for shiningpanda)
Use uuid4() to generate BNode ids. Fixes issue #185
Align bnode_uuid's output with UUID format. Drop 'id-' prefix in favour of '_'.
Added documentation for handling of bnode IDs in set-theoretic graphs-ops. fixes #195
Bertrand's fix for serialize to file 'IOError: File not open for writing' error
moving towards 3.2.1, updated changelog/contributes/licesen. fixes #194
optimisations - generation-comprehensions instead of list-comprehensions
released 3.2.1
back to dev version number
fixed old google URIs - this is the REAL 3.2.1 :)
back to dev version
Recover thread-protective Rlock for BNode id generation. Fixes issue #209.
Tentatively add test for issue #209.
updated readme - #rdflib irc channel