Add stubs for map scale..
Added scale, hardcoded at 180px, displays meters
Map scale adjusts and displays user-friendly units.
Fix buggy padByMeters (PI/180 is needed here)
remove unnecessary semicolons (jshint)
refactor dLat/dLon <-> meters calcs and use slightly better WGS84 constants
add dLat/dLon <-> meters tests, narrower limits for distance tests.
Drop postcode for Ireland addresses

Per https://github.com/openstreetmap/iD/commit/f2c5dc1d185a7641363a3c2c3ca607e86f051109#commitcomment-6790305
cleanup footer styles, append account links to footer link menu
missing comma..
Merge pull request #2266 from bhousel/bhousel-scale

Add linear map scale to footer section