Using `group` + `color` produces incorrect plot

[alyst]

plotly incorrectly draws lines scatter (and scatter3d) plots.

Consider the following minimal example:

df = data.frame(x=c(1,2,3,4,5,6),
           y=c(1,1,2,2,3,3),
           t=c("A","A","B","B","A","A"))

plot_ly(df, type="scatter", x=x, y=y, color=t, group=y, mode="lines")

The output is:

In the correct plots only the horizontal segments colored according to t column are expected; also no 1,2,3 entries in the legend, A and B sorted either alphabetically or by their appearance in the data frame.

[cpsievert]

I have a note of this here as well #381

I hope to get to this soon...thanks for the minimal example!

[alyst]

@cpsievert Yes, it's the same as #381 + an additional issue of drawing "parasitic line" (2,1) - (5,3).