Align logger

Align the messages between log messages with different length level text. Added an extra format $levelpad, which is a space if the level is "warn" or "info".

So, basically

```
12:34:56.123 [info] a message from the logger
12:34:56.123 [error] a message from the logger
12:34:56.123 [debug] a message from the logger
12:34:56.123 [warn] a message from the logger
```

becomes

```
12:34:56.123 [info]  a message from the logger
12:34:56.123 [error] a message from the logger
12:34:56.123 [debug] a message from the logger
12:34:56.123 [warn]  a message from the logger
```