EXPORTX3D Export the mesh into X3D format

       exportX3D(filename, vertices, mesh, value, colormap)

 DESCRIPTION:

       Export the mesh to X3D format for use in e.g. 3d modeling
       software.  The mesh has to be a three dimensional, i.e. to
       consists of tetrahedrons. Each tetrahedron will be stored as 4
       triangles.  The triangles will be colored according to
       'colormap' and 'value'. The length of 'value' is equal to the
       number of tetrahedrons

 USAGE:

       exportX3D('mouse.x3d', vmcmesh.r,vmcmesh.H, solution.element_fluence, @parula)
       exportX3D('mouse.xhtml', vmcmesh.r, vmcmesh.H, solution.element_fluence, @jet)

 INPUTS:

       filename       - see usage example
       vertices       - vector for node coordinates
       mesh           - tetrahederal mesh: indices to vertices
       value          - value for each tetrahedron
       colormap       - colormap function for determining the
                        color of each triangle from 'value'


  This function is provided with ValoMC