In setup.py, get version without loading the whole textile package.

Loading the package in setup.py is unnecessary,
and will fail if dependencies are not installed yet.

setup.py

@@ -1,8 +1,7 @@
 from setuptools import setup, find_packages
+import os
 import sys
 
-from textile import __version__
-
 install_requires = []
 
 try:
@@ -15,9 +14,17 @@
         'tox',
     ])
 
+def get_version():
+    basedir = os.path.dirname(__file__)
+    with open(os.path.join(basedir, 'textile/version.py')) as f:
+        VERSION = None
+        exec(f.read())
+        return VERSION
+    raise RuntimeError('No version info found.')
+
 setup(
     name='textile',
-    version=__version__,
+    version=get_version(),
     description='Textile processing for python.',
     url='http://github.com/ikirudennis/python-textile',
     packages=find_packages(),

textile/__init__.py

@@ -1,5 +1,6 @@
 from .core import textile, textile_restricted, Textile
+from .version import VERSION
 
 __all__ = ['textile', 'textile_restricted']
 
-__version__ = '2.1.8'
+__version__ = VERSION

textile/version.py

@@ -0,0 +1 @@
+VERSION = '2.1.8'