title: How to set zoom level of a Google map according to marker locations
body: <p>I have placed two markers on a Google map. One is in the USA and other one is somewhere in Asia. Google only gives zoom levels 1, 2, 3, 4, 5, 6, etc.</p>
  
  <p>I don't want to hard-code the zoom level. How can I display all markers depending upon distance? I.e. if two items are very close to each other or in the same city, a close zoom level should be used, and if they're far apart, then maximum zoom level should be used.</p>