Unusual line number and column format in output

Sail gives the complete line and column range for error messages by default:

```
Warning: Redundant case sail-riscv/model/riscv_sys_control.sail:206.6-7:
206 |      _ => false
    |      ^
```

Laudable, but this is an unusual format that tools like IDEs don't recognise by default. Would you accept a PR changing it to the far more standard format `filename:line:column:`?