Highlight punctuation that does not fall into any syntax group

[kynikos]

Hi, I was wondering if you were interested in merging this patch: it creates a group (pythonPunctuation, disabled by default) for generic punctuation characters that is tested before any other group, so that only the text outside of any group is affected. I'm not sure if I'd also be required to edit CHANGES.txt or the files under folding-ideas/.