Massive spaces->tabs and trailing whitespace cleanup, hopefully for the last
time now I've configured emacs to make them displayed in really annoying
colours...
Add a per-client log of status line messages displayed while that client
exists. A new message-limit session option sets the maximum number of entries
and a command, show-messages, shows the log (bound to ~ by default).
This (and prompt history) might be better as a single global log but until
there are global options it is easier for them to be per client.
