Added MatCap from zBrush using SEM (spherical environment

mapping to emulate materials on meshes) - reflection mapping. material
files .jpg/.pngs can be updated by entering into text field and pressing
enter. clipping range changed to 0.1/1000. interactor allows testing of
evalsuperquad using 's' to get segmented superquad points, interactor
also allows testing of creating hinge-ring using
vtkintersectionpolydatafilter and 'k', shader takes in matcap, and
computes a mix of final_color with matcap. water shader knows superquad
info?