Genshi doesn't export version information

[techie]

>>> import genshi
>>> genshi.__version__
Traceback (most recent call last):
  File "<stdin>", line 1, in ?
AttributeError: 'module' object has no attribute '__version__'
>>>

[cmlenz]

If you have setuptools, and have installed Genshi using setuptools (which is the default when setuptools is found when you run setup.py), you can do:

import pkg_resources
pkg_resources.get_distribution('Genshi').version

This could probably be done in __init__.py, but I'm not sure what to do when Genshi is installed without setuptools—which is still an option.

[cmlenz]

[516] adds the __version__ attribute for a setuptools-based install. I don't really want to have multiple places to change the version number, so this will have to do for now.