Poor error message when forgetting the bang in a macro.

``` rust
fn main() {
    for i in 1..10 {
        println("{}", i);
    }
}
```

yields (on playpen):

```
<anon>:3:9: 3:16 error: unresolved name `println`. Did you mean `iter`?
<anon>:3         println("{}", i);
                 ^~~~~~~
error: aborting due to previous error
playpen: application terminated with error code 101
```

which is not helpful.
