title: Change Dapper so that it maps a database null value to double.NaN
body: <p>I have a nullable double column in my SQLite database.</p>
  
  <p>When reading from the database (for columns of type double) I would like to convert nulls into "double.NaN".</p>
  
  <p>Currently dapper sets null values to 0, which I do not want.</p>
  
  <p>What are my options?</p>
  
  <ol>
  <li>Modify Dapper source code. </li>
  <li>Can't use Dapper, need to write my own ADO.NET code the old fashioned way?</li>
  <li>change the way that I call the cnn.Query method, to modify the way that mapping happens.</li>
  </ol>
  
  <p>My first choice is option 1, but I need help modifying Dapper.</p>