Currently OfflinePlayer#getLastPlayed could more accurately be described
as "OfflinePlayer#getLastTimeTheirDataWasSaved".
The API doc says it should return the last time the server "witnessed"
the player, whilst also saying it should return the last time they
logged in. The current implementation does neither.
Given this interesting contradiction in the API documentation and the
current defacto implementation, I've elected to deprecate (with no
intent to remove) and replace it with two new methods, clearly named and
documented as to their purpose.
