Simple Extrusion crash

[DavidAKopriva]

HOHQMesh now crashes with a set fault when extruding a 2D mesh that has been generated without an outer boundary. An example control file is for a 2D box extruded to a cube geometry: \begin{CONTROL_INPUT}

\begin{RUN_PARAMETERS} mesh file name = MeshFiles/Box3D.mesh plot file name = PlotFiles/Box3D.tec stats file name = None mesh file format = ISM polynomial order = 4 plot file format = skeleton \end{RUN_PARAMETERS}

\begin{MESH_PARAMETERS} element type = hex \end{MESH_PARAMETERS}

\begin{SIMPLE_EXTRUSION}
  direction          = 3
  height             = 2.0
  subdivisions       = 3
  start surface name = bottom
  end surface name   = top

\end{SIMPLE_EXTRUSION}

\begin{BACKGROUND_GRID} x0 = [0.0, 0.0, 0.0] dx = [1.0, 1.0, 1.0] N = [5,5,5] \end{BACKGROUND_GRID}

\begin{SPRING_SMOOTHER}
   smoothing            = ON
   smoothing type       = LinearAndCrossBarSpring
   spring constant      = 1.0
   mass                 = 1.0
   rest length          = 0.0
   damping coefficient  = 5.0
   number of iterations = 5
   time step            = 0.1

\end{SPRING_SMOOTHER}

\end{CONTROL_INPUT}