Change algorithm in TPad::RecalculateRange computing the constant factor

for the transformation to pixel coordinates. Do not use the offset=0.5
but instead a small rounding offset = 0.00005.
This fixes the problem of the axis lines not coinciding with the pad frame lines.


git-svn-id: http://root.cern.ch/svn/root/trunk@5425 27541ba8-7e3a-0410-8455-c3a389f83636