rustdoc type paths contain zero-width spaces

E.g. go to http://doc.rust-lang.org/std/option/type.Option.html and copy the path contained in: "Enum std​::option​::Option​". If you paste it into a Rust source file, you'll get an error along these lines:

```
<anon>:18:16: 18:17 error: unknown start of token: \u200b
<anon>:18         use std​::option​::Option​;
```

That character is the zero-width space.

This is highly inconvenient.
