PyTypeObject members tp_compare, tp_richcompare, tp_base

Conflicts:
	tests/run/generators.pyx

prevent generator methods from returning NULL without setting an exception: method call protocol differs from __next__() protocol

remove test that doesn't apply to normal Python (only to the corresponding .pyx test where it remains)

Conflicts:
	Cython/Compiler/ExprNodes.py

mofe GIVEREF() before PyTuple_SET_ITEM() call because that's when we still own the reference (pypy needs it that way)

patch Generator ABC into "collections.abc" when using Cython generators so that foreign code can test for the Generator protocol instead of the generator type

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.