hmm, thinking about it - adding a couple of extra functions that won't be used on win/mac doesn't appeal to me. actually, it looks like returning "multipath" (paths separated by os.pathsep) is already a good workaround. this is what you already have. 

though, can we rename `returnlist` to `multiple`? as in:

```site_data_dir(multiple=True) => "/usr/local/share:/usr/share"```