Support for point fill and border thickness in scatterPlot

[j-andrews7]

E.g.

df <- data.frame(id=runif(12), x=1:12, y=runif(12))
ggplot(df, aes(x=x, y=y)) + 
  geom_point(aes(fill=id, size=id), colour="black", shape=21, stroke = 2)

This would require some adjustments to how color.by is interpreted (to switch it to populate the fill aes instead) and addition of parameters to control stroke width and color (when fill is populated rather than color by color.by). Potentially confusing changes, as we'd only want it to work with the open shapes (21-25).

Would be interested in how you'd prefer something like this be implemented.

[dtm2451]

I'll have to think about this some more. But yea, maybe something like outline.size and outline.color for the inputs? Maybe with '.by' too... I think it'd be nice to let these be populated from a column if the value given matches a column name. Probably both default to NULL and when they are left NULL is when the current system stays.

For shape switching... perhaps the shape.panel default value should change to NA and, unless set by the user, it then gets filled in with a different set of shapes depending on which coloring.