add backlog_max_age feature
I like to get history when I reconnect, but only up to a point. It gets a bit ridiculous when I have messages from 2 hours ago that I want to see, yet also end up receiving messages from 3 months ago that I don't care about any more. Could someone add a feature to limit the backlog to a maximum age? For example, it'd be nice to see only the messages which happened within the past 30 days. The blreset command is not really sufficient here, since it gets rid of both recent and old messages.
Ideally, bip should replay messages which are less than backlog_max_age days old, up to a maximum of backlog_lines lines per channel (or per query).
Depending on other users' preferences, it might be better to specify the max age in terms of hours instead of days. I can set it to 30*24 hours easily enough for a value of 30 days, but it's not so simple to set it to 1/24 days for a value of one hour.