[Feature Request] Extracting values from insert query for multi rows

hello, I have a Feature Reques, please check if necessary

```python
from sql_metadata import Parser
parser =  Parser("INSERT INTO (field1,field2) VALUES (1,2), (1,2);")
print(parser.values_dict) #{'field1': 1, 'field2': 2}
```

the value of parser.values_dict  can be a list?
{'field1': [1,1], 'field2': [2,2]}

