The file plantuml.jar is downloaded from Sourceforge and saved as
"plantuml.jar" in the folder system.file("jar", package =
"plantuml") of the package. The source code for plantuml can be
found at https://github.com/plantuml/plantuml
plantuml_update(tag = "release", ...)tag of the version to be downloaded. Allowed values are
"release : the last release
"snapshot" : the last snapshot - Not ready for gneral use
additional arguments for the download.file() function
the path and name of the downloaded file
if (FALSE) {
plantuml_update()
}