Revert "Escape local variables in generated pickle helper functions to prevent conflicts with the user defined class name."

This reverts commit a158967e.

Escape local variables in generated pickle helper functions to prevent conflicts with the user defined class name.

Closes #1786.

Issue #1784, Fix string method in Skylark pyx_library

jdemeyer -> Jeroen Demeyer

Add basic support for std::function

Don't use CPython PyMethodDescrObject.

Repair compile time complex expressions

Fix complex comparison

Add declarations for PyObject_GenericGetAttr and PyObject_GenericSetAttr

This brings the overhead to about 10%, or 20ns per traceback.

use faster __Pyx_PyObject_GetAttrStr() implementation and avoid stati…

allow enabling/disabling C line display in tracebacks with a new C compile time macro CYTHON_CLINE_IN_TRACEBACK=0/1

repair comparison between C complex types and extension types: previously generated an invalid type check

extract C-line handling from AddTraceback() into separate function to keep AddTraceback() available as a shared header file

use faster __Pyx_PyObject_GetAttrStr() implementation and avoid static Python string reference in AddTraceback() helper

See #1719.

repair __Pyx_CallUnboundCMethod1() macro which also needs to adapt to the new CPython FASTCALL signature in Py3.7