TGLLegoPainter
   "e" option added for cartesian
   bar width/offset added for cartesian
TGLPlotPainter
   normals for trapezoids in polar/cylindrical/spherical
   coordinates are better now, so lego is "smoother".


git-svn-id: http://root.cern.ch/svn/root/trunk@15467 27541ba8-7e3a-0410-8455-c3a389f83636