Seems like external loggers might find it useful too.

Maybe the log level could just be

```rust
pub struct LogLevel {
    pub level: u32
}
```

which implements `Show` as a string, but still provides easy access to the internal number. (I guess the field could be private too, and offer a retrieval method.)

(In any case, with or without any of these changes, this should be storing a `LogLevel`, not a `u32`.)