- made generic the message that the same xy and z units are required


git-svn-id: svn://svn.code.sf.net/p/gwyddion/code/trunk/gwyddion@16863 25697fe4-d644-49b8-9d30-be5465f2adf3
- added a missing initialised to the defaults


git-svn-id: svn://svn.code.sf.net/p/gwyddion/code/trunk/gwyddion@16864 25697fe4-d644-49b8-9d30-be5465f2adf3
- added a very simple SEM image simulation presentation


git-svn-id: svn://svn.code.sf.net/p/gwyddion/code/trunk/gwyddion@16865 25697fe4-d644-49b8-9d30-be5465f2adf3