From Olivier: - Complete rewrite of TArrow::PaintArrow. The previous version used the   pixel coordinates. This method generated many rounding errors. The   visible effects on arrows were:     1) distorted arrows' heads     2) misplaced arrow compared to a Tline at the same coordinates.   The new TArrow::PaintArrow version fixes these two problems. Instead of   using pixel coordinates it uses "true NDC" coordinates. The "ROOT NDC   coordinates" are not appropriatein this case because X an Y axis are not normalized   the same way, therefore angles are not kept during a rotation.
From Olivier:
- Complete rewrite of TArrow::PaintArrow. The previous version used the
  pixel coordinates. This method generated many rounding errors. The
  visible effects on arrows were:
    1) distorted arrows' heads
    2) misplaced arrow compared to a Tline at the same coordinates.
  The new TArrow::PaintArrow version fixes these two problems. Instead of
  using pixel coordinates it uses "true NDC" coordinates. The "ROOT NDC
  coordinates" are not appropriatein this case because X an Y axis are not normalized
  the same way, therefore angles are not kept during a rotation.


git-svn-id: ecbadac9c76e8cf640a0bca86f6bd796c98521e3@12352 27541ba8-7e3a-0410-8455-c3a389f83636

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