Although tar is a Nix based (and mostly used) format, it gains popularity on Win too.

As tarfile is running on Win, I think it should handle (work around) path incompatibilities, as zipfile (`ZipFile._sanitize_windows_name`) does.

Applies to all branches.

More details on [Tarfile/Zipfile extractall() changing filename of some files](https://stackoverflow.com/questions/55340013/tarfile-zipfile-extractall-changing-filename-of-some-files/55348443#55348443).

Regarding the current zipfile handling: it also can be improved (as it has a small bug), for example if the archive contains 2 files ("file:" and "file_") it won't work as expected. But this is a rare corner case.

I didn't prepare a patch, since I did so for another issue (https://bugs.python.org/issue36247 - which I consider an ugly one),  
 and it wasn't well received, also it was rejected (for different reasons). If this issue gets the green light from whomever is in charge, I'll be happy to provide one.