Added PyPy 3 to the build matrix

add "meteor_contest" benchmark as demo of a program that Cython cannot speed up very much as the bulk of the work (set operations) is in CPython's own code

Use all distutils config files in pyximport

--HG--
extra : amend_source : 738af7da4118ace0e2c39d0883e89db8833b5cbb

add support for C++ stdlib heap operations

enable the C compiler to distinguish between the two for-in iteration cases (special case for list/tuple and generic iterator case)

make SwitchTransform return True/False as result when Python objects are requested instead of crashing when trying to cast bint values to PyObject*

fix isinstance(x, (A,B)) split optimisation: must set up BoolBinopNode correctly when creating it after type analysis

support non-Python-builtin types in Jedi generated declarations by using name strings instead of bare types