Change attribute names in cvmix_data_type to be more human-readable. At this stage, the shared library compiles but I haven't updated any of the stand-alone driver files so I haven't tested the changes yet... As with the change to Mdiff, Tdiff, and Sdiff, I'll update the stand-alone stuff in next commit (later tonight or over the weekend) and then have a bunch of small commits to make sure all the reg_test scripts still work.