Pip install fails due to missing dependency on Cython

[trainman419]

When installing on OSX with pip, the build fails if Cython is not installed. This is probably fixable by declaring Cython as a build-time dependency in the setup.py.

Build log:

$ sudo pip install dubins
Password:
Downloading/unpacking dubins
  Downloading dubins-0.8.tar.gz
  Running setup.py egg_info for package dubins
    Could not find cython, install it first
    Traceback (most recent call last):
      File "<string>", line 16, in <module>
      File "/private/tmp/pip_build_root/dubins/setup.py", line 4, in <module>
        from Cython.Build import cythonize
    ImportError: No module named Cython.Build
    Complete output from command python setup.py egg_info:
    Could not find cython, install it first

Traceback (most recent call last):

  File "<string>", line 16, in <module>

  File "/private/tmp/pip_build_root/dubins/setup.py", line 4, in <module>

    from Cython.Build import cythonize

ImportError: No module named Cython.Build

----------------------------------------
Cleaning up...
Command python setup.py egg_info failed with error code 1 in /private/tmp/pip_build_root/dubins
Storing complete log in /Users/hendrix/Library/Logs/pip.log

[AndrewWalker]

Should be fixed in 0.8.1. Solution used based on the stackoverflow question http://stackoverflow.com/q/4505747/2246