- Implemented z and w units parsing, graphs should be loaded correctly now

git-svn-id: svn://svn.code.sf.net/p/gwyddion/code/trunk/gwyddion@16707 25697fe4-d644-49b8-9d30-be5465f2adf3
- disable OK on a puerly numeric experssion
- this have never worked and has unclear semantics


git-svn-id: svn://svn.code.sf.net/p/gwyddion/code/trunk/gwyddion@16708 25697fe4-d644-49b8-9d30-be5465f2adf3