allow axes to be flipped with parallel coordinates

[rvberloo]

Hi,
we are moving from D3.js parallel coordinates (http://syntagmatic.github.io/parallel-coordinates/) to plotly.js and found that most of our needs are catered already. But the very basic option to flip an axis (see minimal example via link above, doubleclick on axis label) does not seem to be present in the plotly.js parallel coordinate chart. It is very useful to get a 'nicer' more consistent view of the data when there are complementary data in neighbouring axes. Could you consider adopting the axis flipping option in the parallel coordinates chart of plotly.js?