Keyword not found recommendations

For issue #888.
I had noticed that without this unicode normalization, `difflib` would not match `Similär Kw` to `Similar Kw`, while it would match it otherwise. My comment doesn't seem to be an accurate description of what's going on, though, after a quick experiment:
```python
In [5]: s = u'hyvää öytä'

In [6]: repr(s)
Out[6]: "u'hyv\\xe4\\xe4 \\xf6yt\\xe4'"

In [7]: s2 = ''.join(x for x in unicodedata.normalize('NFKD', s))

In [8]: repr(s2)
Out[8]: "u'hyva\\u0308a\\u0308 o\\u0308yta\\u0308'"

In [9]: s2
Out[9]: u'hyva\u0308a\u0308 o\u0308yta\u0308'
```
Anyway, I can leave unicodedata out, since matching non-ASCII strings to ASCII strings is a rare use case.