! Bug fix: don't just ignore any previous topics columns.

Signed-off-by: Peter Spicer <sleeping@myperch.org>
! When merging topics, reuse those topic ids as redirections. While this does require making a new message, let's just keep it at a single line so nothing freaks out too much with it. Should fix #1284

Signed-off-by: Peter Spicer <sleeping@myperch.org>