Supports Pandas (Python)

To easily transform a query result to a [Pandas Dataframe](https://pandas.pydata.org/pandas-docs/stable/reference/api/pandas.DataFrame.html)
the SessionDataSet has a method `.todf()` which consumes the dataset and transforms it to a pandas dataframe.

Example:

```python
from iotdb.Session import Session
ip = "127.0.0.1"
port_ = "6667"
username_ = 'root'
password_ = 'root'
session = Session(ip, port_, username_, password_)
session.open(False)
result = session.execute_query_statement("SELECT * FROM root.*")

1. Transform to Pandas Dataset
   df = result.todf()
   session.close()
2. Now you can work with the dataframe
   df = ...
   ```