Display distance to book on search results

[richard-jones]

We can calculate this in a number of ways, see:

http://www.movable-type.co.uk/scripts/latlong.html

Probably for the distances involved it will be sufficient to use pythagoras

[richard-jones]

Implemented using the following rules:

• Pythagoras theorem, so not taking into account curvature of the earth or anything like that. This has been tested for likely distances we'll see in the system and is still highly accurate
• Rounding the distances to whole miles if > 5 miles away, or to 1 decimal place if < 5 miles away

[richard-jones]

Make it deal with the case when the user's lat/lon is not recorded