adjusted callLater priority
now rendering polylines instead of individual segments
added optional continuingLine parameter to drawDoubleCurve()
Changed "Add X" to "+ X" in tools/data menus
Now using data coordinates instead of pixel coordinates for
left/right margins around parallel coordinates axes.
Removed zoomToSubset option.
Now rendering lines with missing data better.
renamed ParallelCoordinatesPlotter -> OldParallelCoordinatesPlotter