Implemented basic EasyRdf_Isomorphic class
Made EasyRdf_Serialiser_Ntriples::serialiseValue() public
Merge pull request #158 from scor/test_0278

content attribute takes priority over the datetime attribute in RDFa
Implemented bijection calculation code (#121)
Merge branch 'master' of github.com:njh/easyrdf
RDFa 1.1 no longer processes the HTML5 value attribute