Handling clock differences

[ilikejames]

When there is clock difference between the client server, the offset is wrong.

This can be tested by changing the lib/ntp.js ntp:server_sync to:

socket.emit('ntp:server_sync', { t1     : Date.now() + 8000 /* clock 8 seconds a head from client */,
                                 t0     : data.t0 });

The proposed change is to update the client js file so that the diff is calculated by:

var diff = Date.now() - data.t1 + ((Date.now() - data.t0)/2);