character string: the package name and directory name for your package.
list
character vector naming the R objects to put in the package.
Usually, at most one of "list", "environment", or "code_files" will be supplied. See "Details" of package.skeleton.
environment
an environment where objects are looked for. See "Details" of package.skeleton.
path
path to put the package directory in.
force
If "FALSE" will not overwrite an existing directory.
code_files
a character vector with the paths to R code files to build the package around. See "Details" of package.skeleton.