Remove old unused undo_filter wrap.
unfilter_scanline now completely replace it and renamed to undo_filter.
Also filter_scanline renamed to _filter_scanline to indicate that it shouldn't be called directly in most cases.
Self-runnable test_png.py
Separate copyBarray function
Rework import to less complicated
Missed caching of previous line
Add PIL License as idea of PIL plugin taken from PIL
Keeping list of releases seems badly compatible with multi-branch support
Update README.txt
Update ignore list
Without list of releases and with doc on readthedocs special release procedure doesn't seem really needed.
More travis matrix, allow cython fail on pypy