text: Title: Add click handler to GeoJSON features
  Body: Hi, 
  
   I am using your Gmaps package for data visualization in my research. It's a great package. I appreciate you taking the time to prepare it.
  
   In the main page, you have mention the "interactive" feature of the package. Is there a click event that I can use? I want to have a click event so when the user clicks on a polygon, the colors of other polygons changes.