Allow collection of server statistical data #196
Because of the recent increase in the update rate of Syncplay, we would like to have some data on our currently user base.
This PR introduces a new server argument
We only store non-sensitive and non-personal data that are already being transmitted by the clients in the current protocol. Specifically, for every user in the server at the time of stats collection, we store (EDIT):
Data collection is scheduled to happen every hour. Nothing else is acquired nor stored in the snapshot.
Thanks to SQLite, full concurrency is supported and multiple servers can use the same DB file at the same time. For further safety, a fixed delay is introduced before the first collection, and its amount is based on the server's port number. (EDIT):