Waiting for a response after the response

https://github.com/cs01/pygdbmi/blob/bee475b8951c3ea2e8bb1339b2c856a291fb7d7d/pygdbmi/gdbcontroller.py#L291

Hello! If I understand correctly, the one way to exit from mentioned While loop - timeout. Maybe it could be better to add something like

```python
if len(responses) is not 0:
if responses[-1].get('message') == 'done':
break
```
because right now, for example, inserting several breakpoints in windows takes (N_breakpionts * timeout) seconds. GdbController could already have a responce, but continue to wait a timeout.