Zany logon/logoff announcements
Currently we have
- SYSTEM: welshbyte has just entered the board.
But that could have a bit of fun injected into it by generating random (welcoming!) entry announcements, e.g.
- SYSTEM: You rolled two sixes! welshbyte has just entered the board.
- SYSTEM: welshbyte has just pirouetted onto Milliways - how graceful!
- SYSTEM: The prophesy has come true, welshbyte has arrived.
(Inspired by Discord)