Gray design
design_gray()a list with main_color_1, a vector of 12 main_colors, a
corresponding main_contrast_1 (the color of text to write on top of the
main color) and a corresponding main_contrasts, the main_size (for
lines), a comparison_linetype, comparison_color, and comparison_size
for all lines that act as comparative lines, and a ggplot2
theme