Face-to-face: peer-leave notice is invisible and names the Bot; top bar shows the previous room's title after joining #191

From the live resmoke on c56384a (A :3080 @uia1415.home, B :3081 @uib1415.home).

1. When the peer leaves, A's page text contains "UiB1415's Chief left" but nothing is visible in the room view, and it names the Bot rather than the person. Expected: a visible status line in the room naming the person ("UiB1415 left the room. This room is closed.").
2. On B, joining a new room by number leaves the main pane (and its top bar title, e.g. "Face-to-face · UiA1415 · Oct 17 14:38") on the previous room until Enter chat. Expected: the main pane moves to the new room as soon as it is joined.

Related: #182 (leave and titles).