store version string in separate file

setup.py

@@ -1,11 +1,13 @@
 #!/usr/bin/env python
 from distutils.core import setup
 
-import urwidtrees
+# this loads the version string into __version__
+with open('urwidtrees/version.py') as f:
+    exec(f.read())
 
 setup(
     name='urwidtrees',
-    version=urwidtrees.__version__,
+    version=__version__,
     description="Tree widgets for urwid",
     author="Patrick Totzke",
     author_email="patricktotzke@gmail.com",

urwidtrees/__init__.py

@@ -1,10 +1,8 @@
-__version__ = '1.0.3.dev'
-__copyright__ = "Copyright (C) 2016 Patrick Totzke"
-__license__ = "Licensed under the GNU GPL v3+."
-
 from .tree import Tree, SimpleTree
 from .decoration import DecoratedTree, CollapsibleTree
 from .decoration import IndentedTree, CollapsibleIndentedTree
 from .decoration import ArrowTree, CollapsibleArrowTree
 from .nested import NestedTree
 from .widgets import TreeBox
+
+from version import __version__

urwidtrees/version.py

@@ -0,0 +1 @@
+__version__ = '1.0.3.dev'