Increase version number.

As next release will not be pure bugfix any more (we got additional
options), we increase the minor version number.

CHANGES.rst

 Changes
 =======
 
-0.4.1 (unreleased)
-------------------
+0.5 (unreleased)
+----------------
 
 - New option ``-r``, ``--randomsource``. We support a pluggable system
   to define alternative sources of randomness. Currently supported

setup.py

@@ -44,7 +44,7 @@ docs_require = [
 
 setup(
     name="diceware",
-    version="0.4.1.dev0",
+    version="0.5.dev0",
     author="Uli Fouquet",
     author_email="uli@gnufix.de",
     description=(