plot_or() now respects the order of covariates in the formula when plotting
(#15).
plot_or() handles missing information to avoid {ggplot2} related warning
messages (#11).
plot_or() accepts customised confidence limits, e.g. 99%, used when
calculating the confidence intervals (#19).
plot_or() conducts checks on inputs - ensuring the {glm} model is
a logistic regression (family = 'binomial' and link = 'logit') and validates the
confidence limit to be within the range 0.001 to 0.999 (#22, #19).