ggplot2 plots made easy for Multiple correspondence analysis (MCA)

ggplot.acm provides an easy way of creating a ggplot2-style plot for a multiple correspondence analysis run with the FactoMineR package (this is important, as other packages/functions may product objects with a different internal structure). Multiple options are provided, which should adress the most common uses in social sciences. The autoplot.MCA function extends the autoplot generic function, and returns a ggplot2 object, which can then be further modified.