_estimate_time_received should use time_server

[danielrichman]

Some points are out of order. My current favourite is the unnamed listener whose clock is set to exactly the right time and day… in May rather than April.

currently:

• uses time_created provided by the listener, excludes points outside std dev, takes mean

ideas:

• correct time_created by using (time_server - time_uploaded)
• if time_server provided, trust it and ignore others
• weight listeners with time_server provided in the previous algo (4x ?)

[danielrichman]

Draft: danielrichman@b628bbb

TODO: do something with this