graphics/R-cran-ggforce: New port

The aim of 'ggplot2' is to aid in visual data investigations. This focus has led
to a lack of facilities for composing specialised plots. 'ggforce' aims to be a
collection of mainly new stats and geoms that fills this gap. All additional
functionality is aimed to come through the official extension system so using
'ggforce' should be a stable experience.