Introduce DataSet and change demo files to the new type system.
Update API unit tests.
Changes to test_caching.py.
Fix Sparsity cache key
Changes to test_caching.py to work with DataSet.
Fixes test_colouring.
Fixes test_constants.py
Fixes test_direct_loop.py.
Fix test_extrusion.py.
Fixed test_global_reduction.py.
HDF5 tests fix. Changes airfoil and aero demos.
Fixes test_indirect_loop.py
Fixes test_iterations_space_dats.py
Fixes test_linalg.py.
Fixes test_matrices.py
Fixes test_plan.py.
Fixes test_vector_map.py.
Default DataSet dim to 1
Add DataSet default dim test
Rename Dat properties dataset -> set, ddataset -> dataset