Fix Memviewslice docstrings & Test

[#2634] Merge Fix 

Workaround for long internals misconfiguration on 64-bit MinGW.

Also add a compile time check for SIZEOF_VOID_P.

This fixes #2670.

See also
https://bugs.python.org/issue35037
https://bugs.python.org/issue4709

Fix reimport_from_subinterpreter test when PYTHONPATH is set

Correct the handling of line tracing errors on try-statements. Previously, this jumped to the error label of the try-statement, whereas it must target the outer error label instead.
Closes #2274.

Only error out for non-ASCII literals on actual bytes literals

Smarter bounds checks

See https://bugs.python.org/issue28397

Add --3str command line option to 'cython' program

Improve message for deprecated "language=..." option

Fixes #2634

Rename the options of the "check_size" feature to make them more obvious: "warn" warns, "error" fails, and "extend" silently allows extending.
Closes #2627.

Enable "check_size=False" for the NumPy ndarray and dtype extension types to avoid warning about otherwise backwards compatible changes.

Add new "language_level=3str"