Release 0.5.1

```
git shortlog -s -n v0.5.0..v0.5.1
    26  Tobias Schlatter
    16  Sébastien Doeraene
     2  Alexander Myltsev
     1  Matt Seddon
```

That's 15 merge commits and a commit saying "Towards 0.5.1"... I guess that counts :P