- Enums are cleaned a bit

git-svn-id: svn://svn.code.sf.net/p/gwyddion/code@16695 25697fe4-d644-49b8-9d30-be5465f2adf3
- fixed wrong preview update logic in units_in_title_changed()


git-svn-id: svn://svn.code.sf.net/p/gwyddion/code@16696 25697fe4-d644-49b8-9d30-be5465f2adf3