Feature request: A way to fix the scale of venn circles

[beefstew]

Desired: To have circles representing similar counts appear the same size across plots; this is especially true when creating diagrams with multiple subplots.

Currently, the rendered size of a venn circle is based on the length of the sets that are passed into the venn3 function. Depending on your data, this can cause a circle representing 25 items to appear the same size as one representing 500 items on diagrams that appear next to one another.

Suggestion: add a max_set_size parameter that is used to calculate the scaling factor of drawn circles. Users can easily determine a maximum set size for their data and pass it to each separate venn3 call.

Thanks!