Rewrite rendering of jet-cones:  - do not use triangle fan, it does not allow to properly set normal at    the apex for eack triangle;  - enable two-sided lightning.
Rewrite rendering of jet-cones:
 - do not use triangle fan, it does not allow to properly set normal at
   the apex for eack triangle;
 - enable two-sided lightning.


git-svn-id: ecbadac9c76e8cf640a0bca86f6bd796c98521e3@33669 27541ba8-7e3a-0410-8455-c3a389f83636

dawehner/root,dawehner/root,bbannier/ROOT,dawehner/root,bbannier/ROOT,bbannier/ROOT,bbannier/ROOT,dawehner/root,bbannier/ROOT,dawehner/root,bbannier/ROOT,dawehner/root,dawehner/root,bbannier/ROOT,dawehner/root