* TGLFaceSet

  Add static flag fgEnforceTriangles and function 'void EnforceTriangles()'.
  When fgEnforceTriangles is set, all tesselations will be automatically
  converted into triangle-only meshes.
  This is needed to export TGeo shapes and CSG meshes to external
  triangle-mesh libraries that can not handle arbitrary polygons.

* TGLUtil
  White-space.

* csgdemo.C
  Use the same number of segments for display and export.


git-svn-id: http://root.cern.ch/svn/root/trunk@34932 27541ba8-7e3a-0410-8455-c3a389f83636