Make bin/c and bin/compare work on Windows.
  - Call python explicitly.
  - Drop numpy dependency (on numpy.mean.... come on.)
  - Make scipy dependency optional.

Depends on https://codereview.chromium.org/1419073003 to really work.

BUG=skia:

Doesn't change code.
NOTRY=true

Review URL: https://codereview.chromium.org/1416833004
2 files changed