doc generation fails on windows
```
[...]
reading sources... [ 75%] io
Exception occurred while building, starting debugger:
Traceback (most recent call last):
  File "c:\portabel\python27\lib\site-packages\sphinx\cmdline.py", line 246, in
main
    app.build(force_all, filenames)
  File "c:\portabel\python27\lib\site-packages\sphinx\application.py", line 212,
 in build
    self.builder.build_update()
  File "c:\portabel\python27\lib\site-packages\sphinx\builders\__init__.py", lin
e 214, in build_update
    'out of date' % len(to_build))
  File "c:\portabel\python27\lib\site-packages\sphinx\builders\__init__.py", lin
e 234, in build
    purple, length):
  File "c:\portabel\python27\lib\site-packages\sphinx\builders\__init__.py", lin
e 134, in status_iterator
    for item in iterable:
  File "c:\portabel\python27\lib\site-packages\sphinx\environment.py", line 470,
 in update_generator
    self.read_doc(docname, app=app)
  File "c:\portabel\python27\lib\site-packages\sphinx\environment.py", line 621,
 in read_doc
    raise SphinxError(str(err))
SphinxError: 'utf8' codec can't decode byte 0x84 in position 25: invalid start b
yte
```

The problem is the following line in io.rst:

```
   data = 'word,length\nTr\xe4umen,7\nGr\xfc\xdfe,5'
```
