parcoords + hovermode modebar button bug

[alexcjohnson]

Deselected lines disappear after you click "toggle show closest data on hover" a couple of times.
https://codepen.io/mobigliani/pen/bmqVgZ
They come back as soon as you re-filter (drag one of the selection regions, or create a new one).

Also if I select only a small region at the bottom, sometimes the selection region gets reset to the whole range, but this does not seem to recalculate the selected lines. I have only seen this on the first column, and even there it seems to be intermittent.

[alexcjohnson]

The deselected lines also disappear if I relayout some other simple attribute, like:

Plotly.relayout(gd,'paper_bgcolor','#eff')

[alexcjohnson]

Closed in #3123