remove 'from datetime cimport *' line from cpython/__init__.pxd as it refers to a separate module, not the core C-API

--HG--
extra : rebase_source : bafa0a661abe97868fe254b3ce2b5e63b8654990
update setup.py script to use cythonize()

--HG--
extra : rebase_source : 6494c60e7f79a9cc85fe72a7adf325557f6de2be
prepare release of 0.19.1
Add relative extern files to dependencies.
Fix build_dir test.
Update release notes.
minor code cleanup
fix build_dir copying in Py2.[45]
more code cleanups
extend build_dir test in a way that I think should work but doesn't
int -> Py_ssize_t in cpython pxd files
fix optimisation of isinstance(X, type)
changelog
a bit too overzealous in converting int to Py_ssize_t
Merge pull request #224 from gandalf013/pyssize_t

int -> Py_ssize_t in cpython pxd files
Fix build_dir extended test case.
More efficient find_root_package_dir.
use new Py3.x signature for PyUnicode_DecodeMBCSStateful() declaration
Merge branch 'master' into 0.19.x

Conflicts:
	CHANGES.rst
fix release date