Fix png images for compass sprite generator

convert-png-to-rgba.py

#!/usr/bin/env python
#
# Script to convert png files to RGBA color space
# Requires Pillow (pip install Pillow)
#
import os
import fnmatch
from PIL import Image

for root, dirnames, filenames in os.walk('sprites'):
    for filename in fnmatch.filter(filenames, '*.png'):
        image_path = os.path.join(root, filename)
        print image_path
        Image.open(image_path).convert('RGBA').save(image_path)

This is the only evidence of the problem that I have found: https://groups.google.com/forum/#!topic/compass-users/U6xMb5INZhA