added tests for pie()
added tests for plot.data.frame(); added support for line end, mitre, and join EVERYWHERE
added test for plot.default
added tests for plot.design; added test for multiple-page output in plotdiff(), in which case only compare the final page
added tests for plot.factor()
added tests for plot.formula()
added tests for plot.histogram()
added tests for plot.table()
fix for plotdiff() handling mutiple-page output
added tests for points(), polypath(), and rug();  added support for font in C_plotXY() when type="p"