golang: Provide __version__

Move version definition from setup.py to golang module so that it is
available at runtime with plain golang.__version__ .

golang/__init__.py

@@ -28,6 +28,8 @@
 ...
 """
 
+__version__ = "0.0.0.dev6"
+
 __all__ = ['method', 'go', 'chan', 'select', 'default', 'defer', 'panic', 'recover', 'func', 'gimport']
 
 from golang._gopath import gimport  # make gimport available from golang

setup.py

 # pygolang | pythonic package setup
 from setuptools import setup, find_packages
+from os.path import dirname, join
+import re
 
 # read file content
 def readfile(path):
     with open(path, 'r') as f:
         return f.read()
 
+# grep searches text for pattern.
+# return re.Match object or raises if pattern was not found.
+def grep1(pattern, text):
+    rex = re.compile(pattern, re.MULTILINE)
+    m = rex.search(text)
+    if m is None:
+        raise RuntimeError('%r not found' % pattern)
+    return m
+
+# find our version
+_ = readfile(join(dirname(__file__), 'golang/__init__.py'))
+_ = grep1('^__version__ = "(.*)"$', _)
+version = _.group(1)
+
 setup(
     name        = 'pygolang',
-    version     = '0.0.0.dev6',
+    version     = version,
     description = 'Go-like features for Python',
     long_description = '%s\n----\n\n%s' % (
                             readfile('README.rst'), readfile('CHANGELOG.rst')),