optimize sorted([a,b,c]) into PyList_Sort call

Emit DL_IMPORT macro for python3

implement PEP 479: replace accidental StopIteration exceptions that exit the generator body by RuntimeError

fix temp leak and crash when assigning a C value to both a Python and C target in a cascaded assignment

clean up regular expression in parser (not problematic as it only matches what the scanner already accepted)

cannot currently enable warning checks for C++ class definition syntax as there are incorrect warnings

extend C++ tests to make sure we do not generate warnings (and fix some warnings that we did generate)

tighten Python-to-C++-reference warning to apply only to C++ classes as target and do not show it by default (usage might be legitimate and/or enforced by an external API)

Generate warning when Python object is used as C++ container reference parameter.

Fixed one error which made it break the test suite. Now it doesn't break, but still needs more test cases to see if the functionality works on all inputs.

--HG--
extra : transplant_source : %C4Y%8Fo%10QD%23%A6%FB%B6%AF%3B%D6%C9%A9%09%C4%0D%A8

Document implicit return value behaviour of cdef functions.