Provides an interface for the "nVenn"" algorithm (Perez-Silva, Araujo-Voces and Quesada (2018),
Removed code referencing RcppProgress.
rsvg and grImport2 are now suggested, as some platforms have trouble with them. If they are installed, the package should work as before. If they are not installed, there is no output to the plot window, but users can still export the result.