dia to sml: move transformation code from dia model

We had a number of utility enumerations etc in the dia model which are
not really part of dia - just accessories required for
transformation. Move them across to the transformation model.
dia to sml: add skeleton of main workflow to model
dia to sml: implement workflow
dia to sml: add a number of tests to workflow
dia to sml: add commented out test and minor fix on graph