Rename `save` -> `save_dnpy` and similarly `load.`
Merge branch 'master' into feature/rename-save-and-load
Change some docstring refs to `.dap` to `.dnpy`.
Improve the docstrings for save/load_dnpy.
Merge pull request #224 from enthought/feature/rename-save-and-load

Rename `save` -> `save_dnpy` and similarly `load`