Faster os.walk()

[fuzzylollipop]

ding, ding, ding, we have a winner.

One of the guys on the team did just this, he re-implemented the
os.walk() logic and embedded the logic to the S_IFDIR, S_IFMT and
S_IFREG directly into the transversal code.

This is all going to run on unix or linux machines in production so
this is not a big deal.
All in all we went from 64+k function calls for 7070 files/dirs to 1
PER dir/file.

the new code is just a little bit more than twice as fast.

Huge improvement!