README: remove non-ascii characters

This prevented setup.py from working on my box:

```
Running setup.py egg_info for package from file:///mnt/ssd/src/3rdpart/colout-0.3
    Traceback (most recent call last):
      File "<string>", line 16, in <module>
      File "/tmp/pip-8at8_o-build/setup.py", line 25, in <module>
        long_description=open('README.md').read(),
      File "/usr/lib/python3.3/encodings/ascii.py", line 26, in decode
        return codecs.ascii_decode(input, self.errors)[0]
    UnicodeDecodeError: 'ascii' codec can't decode byte 0xc2 in position 7436: ordinal not in range
```