title: geohash string length and accuracy
body: <p>if length of geohash string is more, it is more accurate. But is there any direct relationship like if length is 7 it is providing 100 meter accuracy, </p>
  
  <p>i.e.   if two geohash (and either of their bounding box) is having first 7 char matching, both should be near 100 meter etc?</p>
  
  <p>I am using geohash for finding, all near-by location for given geohash, with their distance</p>
  
  <p>Also any directway to calculate distance between two geo-hash? (one way is to decode them to lat/lng, and then calculate distance)</p>
  
  <p>Thanks</p>