Make it a PyPI package.

MANIFEST.in

+include pydensecrf/eigen.pxd
+include pydensecrf/eigen.pyx
+include pydensecrf/densecrf.pxd
+include pydensecrf/densecrf.pyx
+recursive-include pydensecrf/densecrf *

README.md

@@ -16,7 +16,9 @@ and provide a link to this repository as a footnote or a citation.
 Installation
 ============
 
-You can install this using `pip` by executing:
+The package is on PyPI, so simply run `pip install pydensecrf` to install it.
+
+If you want the newest and freshest version, you can install it by executing:
 
 ```
 pip install git+https://github.com/lucasb-eyer/pydensecrf.git
@@ -235,3 +237,18 @@ Common Problems
 ---------------------------------
 
 If while importing pydensecrf you get an error about some undefined symbols (for example `.../pydensecrf/densecrf.so: undefined symbol: _ZTINSt8ios_base7failureB5cxx11E`), you most likely are inadvertently mixing different compilers or toolchains. Try to see what's going on using tools like `ldd`. If you're using Anaconda, [running `conda install libgcc` might be a solution](https://github.com/lucasb-eyer/pydensecrf/issues/28).
+
+Maintaining
+===========
+
+These are instructions for maintainers about how to release new versions. (Mainly instructions for myself.)
+
+```
+# Go increment the version in setup.py
+> python setup.py build_ext
+> python setup.py sdist
+> twine upload dist/pydensecrf-VERSION_NUM.tar.gz
+```
+
+And that's it. At some point, it would be cool to automate this on [TravisCI](https://docs.travis-ci.com/user/deployment/pypi/), but not worth it yet.
+At that point, looking into [creating "manylinux" wheels](https://github.com/pypa/python-manylinux-demo) might be nice, too.

setup.py

 # coding: UTF-8
-from distutils.core import setup
-from Cython.Build import cythonize
+from setuptools import setup
 
 # TODO:
 # - Wrap learning.
 # - Make LabelCompatibility, UnaryEnergy, PairwisePotential extensible? (Maybe overkill?)
 
+
+# If Cython is available, build using Cython.
+# Otherwise, use the pre-built (by someone who has Cython, i.e. me) wrapper `.cpp` files.
+try:
+    from Cython.Build import cythonize
+    ext_modules = cythonize(['pydensecrf/eigen.pyx', 'pydensecrf/densecrf.pyx'])
+except ImportError:
+    from setuptools.extension import Extension
+    ext_modules = [
+        Extension("pydensecrf/eigen", ["pydensecrf/eigen.cpp", "pydensecrf/eigen_impl.cpp"], language="c++", include_dirs=["pydensecrf/densecrf/include"]),
+        Extension("pydensecrf/densecrf", ["pydensecrf/densecrf.cpp", "pydensecrf/densecrf/src/densecrf.cpp", "pydensecrf/densecrf/src/unary.cpp", "pydensecrf/densecrf/src/pairwise.cpp", "pydensecrf/densecrf/src/permutohedral.cpp", "pydensecrf/densecrf/src/optimization.cpp", "pydensecrf/densecrf/src/objective.cpp", "pydensecrf/densecrf/src/labelcompatibility.cpp", "pydensecrf/densecrf/src/util.cpp", "pydensecrf/densecrf/external/liblbfgs/lib/lbfgs.c"], language="c++", include_dirs=["pydensecrf/densecrf/include", "pydensecrf/densecrf/external/liblbfgs/include"]),
+    ]
+
 setup(
     name="pydensecrf",
-    version="0.1",
-    description="A python interface to Philipp Krähenbühl's fully-connected CRF code.",
+    version="1.0rc2",
+    description="A python interface to Philipp Krähenbühl's fully-connected (dense) CRF code.",
+    long_description="See the README.md at http://github.com/lucasb-eyer/pydensecrf",
     author="Lucas Beyer",
     author_email="lucasb.eyer.be@gmail.com",
     url="http://github.com/lucasb-eyer/pydensecrf",
-    ext_modules=cythonize(['pydensecrf/eigen.pyx', 'pydensecrf/densecrf.pyx']),
-    packages=["pydensecrf"]
+    ext_modules=ext_modules,
+    packages=["pydensecrf"],
+    setup_requires=['cython>=0.22'],
+    classifiers=[
+        "Intended Audience :: Developers",
+        "License :: OSI Approved :: MIT License",
+        "Development Status :: 5 - Production/Stable",
+        "Programming Language :: C++",
+        "Programming Language :: Python",
+        "Operating System :: POSIX :: Linux",
+        "Topic :: Software Development :: Libraries",
+        "Topic :: Scientific/Engineering :: Image Recognition",
+        "Topic :: Scientific/Engineering :: Artificial Intelligence",
+    ],
 )
-