has_devel.install_version(package, version = NULL, repos = getOption("repos"),
type = getOption("pkgType"), ...)install. Otherwise, it looks at the list of
archived source tarballs and tries to install ainstall."http://cran.us.r-project.org". Can be NULL to install from local files
(with extension
Possible values are "source", "mac.binary.leopard" and
"win.binary": the binary types can be listed and downloaded
but not installed
install_bitbucket;
install_github;
install_gitorious;
install_git; install_url;
install