Core matrix 0.12.0 support

Hi all, I spent a few hours making changes so that Clatrix compiles with the latest core.matrix (0.12.0) and passes all tests (including both the regular Clatrix test suite and the core.matrix compliance tests. 

Needed to make quite a few changes to make this work (mostly improving handling of 1D vectors) so I hope I haven't broken anything that isn't covered by the tests.