expand ggrepel functionality

[csmiguel]

Summary

I would like to apply ggrepel functionality to piecharts or other features in addition to labels. Specifically, I am using scatterpie. I have been trying without any success to modify the geom_text_repel function to account the radius of the piechart for generating the new non-overlapping xy coordinates. I have not been successful however.

I would appreciate ideas to modify the function (or create a new one) that is fed with a vector of sizes for any given feature (i.e. radius of pies) to return new non-overlapping coordinates, which can be latter used to plot the set of features.

[slowkow]

This is a duplicate of issue #83.

I'm working on this in a new branch called point.size. Feel free to try it out, but I do not guarantee that it will work for you. I hope to finish it this year. Contributions welcome.