Known Bugs:
* having an expression in the category names prints, but is left aligned with multiple lines instead of centred
* very weird bug when only a single element in one circle.  Here is a test-case
venn.diagram(list(A=c(5,45,46,57), B=c(42), C=c(4,42,56,63)), filename = 'x.tiff');

Improvements to make:
* Refactoring all of the draw.'code'.R files to condense them down into a few select files, or even a single one
* COMMENT COMMENT COMMENT
* Structure the various functions so that they have identical parameter structures where possible
* Move away from scalars for areas and convert everything, where possible, to vectors and lists
* Add functionality into the venn.diagram function so that it will save in a specific file type given an appropriate file extension (BoutrosLab.plotting.general has a good solution)
* There may be a non-unique solution to the triple-Venn scaling problem as implemented in Vennerable (https://r-forge.r-project.org/projects/vennerable/)
* Allow returning of a data-structure giving the overlaps in each category
* Weirdness in venn.diagram help in the PDF version with lack of wrapping in the parameter-table
