Bugfix/demtests

[jmpearl]

Summary

• Sean caught some errors in the DEM test scripts not included in the ats. This PR updates those scripts.
• It does the following:
  • updates 3 DEM test scripts which were broken
  • Removes one duplicate DEM test script that was defunct
  • fixes the distance method of the RectangularPlanarSolidBoundary

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ToDo :

• Annotate RELEASE_NOTES.md with notable changes.
• Create LLNLSpheral PR pointing at this branch. (PR#)
• LLNLSpheral PR has passed all tests.

[jmikeowen]

Overall these changes look good. My only request would be to replace the locally defined sign functions with the generic ones we provide in the Utilities directory.

[jmikeowen]

Good to go