Development of AnalysisSuite (including tests) will now assume the presence of nat.as package
All AnalysisSuite users now require nat package

* which brings nat.utils with it
cmtk.mat2dof and cmtk.dof2mat have been moved to nat
remove code to nat (and deprecate left over functions)

* relevant tests still pass
nat: remove mat2dof/dof2mat tests