update source JavaScript library to modular parcoords-es to stay current with d3 and avoid conflicts with other versions of d3
add proxy and methods for control and use of a parcoords htmlwidget from Shiny
rework color argument completely to allow for coloring by a continuous variable and provide more flexibility for future use. Now we can also eliminate htmlwidgets::JS from the argument so that the R user does not need to write JavaScript functions.
allow horizontal scrolling when parcoords bigger than screen
add center method for horizontally centering parcoords based on a column/dimension
add snapshot method to export chart in current state to png
add experimental Breshenham mode mode = 'tiled'