Reduce calls to server for user movement

[dburleson]

Sgeo comments:

Although some things could be cleaned up: A rate limit on sending to server, maybe using WebRTC to lower server's bandwidth usage

User movement is pings at every change, which will cause a huge load on the server with multiple users.Throttling the calls to the server should resolve this. Maybe only ping position every half a 1/10 of a second and only when actually moving.