Creates colour gradient between two hexcodes.
cg(colour1, colour2, n = 15)
A vector of hexcodes of length n, containing a colour gradient between colour =1 and colour2.
cg("white","black",20)
#> [1] "#FFFFFF" "#F1F1F1" "#E4E4E4" "#D6D6D6" "#C9C9C9" "#BBBBBB" "#AEAEAE"
#> [8] "#A1A1A1" "#939393" "#868686" "#787878" "#6B6B6B" "#5D5D5D" "#505050"
#> [15] "#434343" "#353535" "#282828" "#1A1A1A" "#0D0D0D" "#000000"