Timeline Options Helper
timelineOptions(getInterval = NULL, pointToLayer = pointToLayerFun(),
  styleOptions = leaftime::styleOptions(), drawOnSetTime = NULL)htmlwidgets::JS function that returns an object with
start and end properties to specify the start and end
of the timeline range.  See
getInterval.
htmlwidgets::JS function that determines what is drawn
on the map.  By default, a circle marker will be drawn.  See
pointToLayer.
list from link{styleOptions}.
logical to draw when time is set.  Default is TRUE.  See
drawOnSetTime.
list with options to customize the timeline