ggplot formatting for wedge calibration plot.

format_wedgeplot(calib, grp_vars, facet_rows, facet_cols)

Arguments

calib	the output from `compute_calibration()`
grp_vars	variables over which to compare calibration. These determines the color of the lines and faceting depending on `type`
facet_rows	A variable name to facet data over. Creates a separate row of plots for each value of specified variable. Can be used with `facet_cols` to create a grid of plots. Should be passed to plot_calibration when customized.
facet_cols	Same as `facet_rows`, but with columns.

ggplot object