[559365] Fix wrong jump link locations

In PointListUtilities, "long" was used instead of "double". The rounding
was not "critic" for an edge with few segments and/or few jump links,
but the addition of rounding become critical for an edge with a lot of
segments and/or jump links.

Bug: 559365
Change-Id: I3a6455f937c70a6bd54dfe1edb797862e5d556da
Signed-off-by: Laurent Redor <laurent.redor@obeo.fr>