Allow American spelling of "colour" in geom_ref_line

[brianrice2]

It would be nice if geom_ref_line() could handle the American spelling of "colour" too, like ggplot2 does.

Example:

library(tidyverse)
library(modelr)
mtcars %>% 
  ggplot() + 
  geom_point(aes(mpg, hp, color = as.factor(cyl))) +
  geom_ref_line(h = 120, colour = "black", size = 0.5)

mtcars %>% 
  ggplot() + 
  geom_point(aes(mpg, hp, color = as.factor(cyl))) +
  geom_ref_line(h = 120, color = "black", size = 0.5)
#> Error in geom_ref_line(h = 120, color = "black", size = 0.5): unused argument (color = "black")

^{Created on 2020-08-02 by the reprex package (v0.3.0)}

[hadley]

modelr is now superseded, which means that we'll only perform critical bug fixes needed to keep it on CRAN. Thanks for contributing this idea and my apologies that it took so long to inform you that this package is no longer under development.