Log Message:
Update to 0.17.3:

0.17.3:

Bugs fixed
----------

* During final interpreter cleanup (with types cleanup enabled at compile
  time), extension types that inherit from base types over more than one
  level that were cimported from other modules could lead to a crash.
* Weak-reference support in extension types (with a "cdef __weakref__"
  attribute) generated incorrect deallocation code.
* In CPython 3.3, converting a Unicode character to the Py_UNICODE type
  could fail to raise an overflow for non-BMP characters that do not fit
  into a wchar_t on the current platform.
* Negative C integer constants lost their longness suffix in the generated
  C code.

0.17.2:

Features added
--------------

* ``cythonize()`` gained a best effort compile mode that can be used to
simply ignore .py files that fail to compile.

Bugs fixed
----------

* Replacing an object reference with the value of one of its cdef
attributes could generate incorrect C code that accessed the object after
deleting its last reference.

* C-to-Python type coercions during cascaded comparisons could generate
invalid C code, specifically when using the 'in' operator.

* "obj[1,]" passed a single integer into the item getter instead of a \ 
tuple.

* Cyclic imports at module init time did not work in Py3.

* The names of C++ destructors for template classes were built incorrectly.

* In pure mode, type casts in Cython syntax and the C ampersand operator
are now rejected. Use the pure mode replacements instead.

* In pure mode, C type names and the sizeof() function are no longer
recognised as such and can be used as normal Python names.

* The extended C level support for the CPython array type was declared too
late to be used by user defined classes.

* C++ class nesting was broken.

* Better checking for required nullary constructors for stack-allocated C++
instances.

* Remove module docstring in no-docstring mode.

* Fix specialization for varargs function signatures.

* Fix several compiler crashes.