make sure all identifiers are EncodedString objects

This is more consistent with the execution of "python foo.py" and
also allows for compilation of files that don't obey the module
naming rules.

avoid dependency of module patching code on order of utility code sections in C file (had to come after "Generator" code by accident in order to work)

Conflicts:
	CHANGES.rst

fix stupid C-API misuse: accidentally passed a NULL pointer to PyObject_GetItem() instead of a 0 integer index to PySequence_GetItem()

When merging a transitive_list, copy the list

Fix relative cimport for Cython package dirs

avoid "return"-ing from generator without NULL return value but no exception set (fails assertion in debug build)

work around crash in CPython's yield-from implementation for generators that "return" values using a StopIteration exception valu

add another fast-path in generator exit code that avoids exception normalisation of exact StopIteration objects

avoid setting explicit "None" as StopIteration exception value in generators and directly return NULL instead