A better directory iterator and faster os.walk() for Python
Description
scandir() is a directory iteration function like os.listdir(), except that
instead of returning a list of bare filenames, it yields DirEntry objects that
include file type and stat information along with the name. Using scandir()
increases the speed of os.walk() by 2-20 times (depending on the platform and
file system) by avoiding unnecessary calls to os.stat() in most cases.
scandir is included in the Python 3.5+ standard library.
