Ban for a set time until automatic unban

[slook]

Rather than banning until manually unbanned, it would be good to prevent them from coming back for a while, say 10 minutes by default, or a custom value as an optional argument to the ban command.

Suggest storing the minutes (seconds/60) past the epoch plus the number of ban minutes, in the banned column of the users table, such that if the set time set but is in the past then they are no longer banned.

Setting a short time value (1 minute) would be a more effective kick, or that command could be removed in favour of a short ban 1.

In the future, the ban mechanism could be automatically set in the event of repeated login failures, excessive chat spam and other abuses or client bugs (that can be detected using timers to govern the maximum amount of allowed requests per minute) but auto-ban is beyond the scope of this auto-unban feature.

[mathiascode]

An optional argument to the ban command seems reasonable, as well as storing a ban expiration timestamp in the database.