[Cython] Path towards Python completeness

[Stefan Behnel]

Stefan Behnel wrote:
> Robert Bradshaw wrote:
>> http://hg.cython.org/cython-closures/file/c4ee199f08a2/tests/run/closures_T82.pyx
>>
>> Before you get your hopes up too much, I want to add a big
>> disclaimer that though I tried to be careful, this is very first-
>> draft code and there are bound to be issues (e.g. I think I've run
>> into some with respect to Python arguments).
> 
> I'll give it a try during the next days.

I exercised it a bit and added more test cases. That revealed a couple of
problems, although I must say that it works pretty well in general.

I added comments to the tests as far as I got with analysing them. One
segfaults pretty badly, which makes it harder to figure out.

Stefan