I implemented a removal of `trailing` from `whitespace-style` as suggested.

But now I'm getting second thoughts...

`whitespace-style` not only controls what kind of whitespace is visualized but also controls what kind whitespace `whitespace-cleanup` should clean. And now trailing whitespace is not removed if I use `whitespace-cleanup`.

I found out about this when trying out @purcell's [`whitespace-cleanup-mode`](//github.com/purcell/whitespace-cleanup-mode).