Issue 394

Summary
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Addresses issue #394, replacing char prefix with string.

Intended Effect
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Code should perform exactly as before; the only difference manifests
in the screen output which should now not contain the character '\0'.

How to Verify
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Run any model and compare screen output and file output.

Side Effects
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None.  Unit tests pass.

Documentation
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No changes.

Suggested Reviewers
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Anyone.