[553776] Use more precise point to locate a point on a segment The previous commit for this issue, e0f6f2cf [1], adapts some utility methods in LineSeg and PointListUtilities to fix some bugs discovered during the tests. But another field must use double instead of long to have a coherence on all computing. [1] http://git.eclipse.org/c/gmf-runtime/org.eclipse.gmf-runtime.git/commit/?id=e0f6f2cfd79b6a09bc3d5c87a0b5881f7fd11be1 Bug: 553776 Change-Id: I1212e3604df61d3a9c1486af2b8034c1a5c28d30 Signed-off-by: Laurent Redor <laurent.redor@obeo.fr>