Added "Model Units" as default export unit option.
Merge pull request #83 from jimfoltz/develop

Avoid using string comparison in loops
Removed commented code.
Merge pull request #84 from jimfoltz/feat-model-units

Added "Model Units" as default export unit option.
Fixed file reading bug where the UTF-8 flag wasn't being set.
Merge commit 'e4ab0a3977aeee973ba74c34b0c6e8145a8469c8'
Merge pull request #86 from thomthom/master

Fix bug where file unicode flag wasn't being used.
Load SKUI and create a test dialog.
Added menu validation proc for empty model.

Resolved #88
Remove "Export entire model" prompt on export.
Removed messageboxes on import.
Added the remaining widgets to test SKUI window
Indenting
Pruned .strings files of unused texts.
More pruningof .strings files.
Layout of SKUI Export dialog.
Added contant to hold OPTIONS.
SKUI controls set values in OPTIONS hash.
Added methods export and select_export_file
Getting closer to SKUI integration