The VariationalMeshSmoother does not have any test coverage and has fallen out of date. This issue delineates the tasks required to bring it up to date. Tasks will be edited/added as needed.

• Get the (commented out) MeshSmootherTest::testVariationalQuad and MeshSmootherTest::testVariationalTri tests running and passing.
• Add test coverage for other element types.
• Add test coverage for the adaptivity feature of the smoother.
• Add test coverage for metric types that are not uniform.
• Add test coverage for the area_of_interest feature of the smoother.
• General code cleanup/consolidation/refactor to use libMesh APIs instead of hard-coded methods
  • Replace hard-coded quadrature sets with libMesh-provided quadrature sets.
  • Consolidate all the branched logic in a more concise way.
  • Use libMesh-provided solvers instead of hard coded solvers.
• Extend sliding boundary node logic to 3D meshes.
  • Identify sliding boundary nodes in 3D meshes.
  • Extend boundary node correction to 3D meshes.
• Add/Update test coverage for 3D meshes.