#88 Alternate "Segmentation" display style

[Craig Stuart Sapp]

When displaying a time values layer with
the "Plot Type" set to "Segmentation",
a vertical black line which has a thickness
of one pixel is drawn at the segmentation
points (unless the dense model gets activated).

These vertical lines are very useful in
most situations, but it would be nice to
be able to hide them in certain cases (such
as with a toggle box somewhere on the layer
control area for a time values layer).

Attached is an illustration of a case
when it would be nice to be able to
hide the segmentation boundary lines.
In this case the lines are too "busy"
and the visual impact of the data being
shown is decreased. The bottom example
in the attached image shows the desired
effect.

[Craig Stuart Sapp]

Segmentation examples with/without lines