wrapped_enum! - Wrap multiple types into an Enum

This is useful when returning multiple types. Let that be via a `try! / return
Err(..)` or simply to just work on an enum of known types.

Note: All variants must contain exactly one argument - to return 

```
#[derive(Debug)]
pub enum LocalError { AliceDidIt, BobDidIt }

wrapped_enum!{
  #[derive(Debug)]
  /// Document your enums!
  pub enum {
    /// Variants too
    Io(io::Error),
    /// How to deal with things that return Option when you need some verbosity for Err.
    ThisModulesName(LocalError),
  }
}
```