Support c2hs (at least partially)

It'd be really cool if stylish-haskell could support files that uses c2hs.
I'm mainly looking for support for making imports stylish.

The `.chs` files include lines like

``` haskell
{#pointer *channel as ^ newtype#}
```

which naturally doesn't parse with a standard haskell parser.

It'd be ok if stylish-haskell only styled the imports which are not in c2hs style, and ignored or skipped the rest of the file when it encountered a c2hs import.

```
{#import Some.Haskell.Module#}
```