Fix tmux theme and remove old visual status option

Tmux makes too many breaking changes. We won't bother worrying about old
versions so much anymore. What will matter now is making sure config
works for Debian stable.

tmux/tmux.conf

@@ -16,10 +16,6 @@ set-option -g pane-base-index 1
 # History scrollback.
 set-option -g history-limit 9999999
 
-# Display a status line message when activity occurs in a window for which the
-# monitor-activity window option is enabled.
-set-option -g visual-activity on
-
 # Resize the window to the size of the smallest session for which it is the
 # current window, rather than the smallest session to which it is attached.
 set-window-option -g aggressive-resize on

tmux/tmuxcolours.conf

@@ -12,7 +12,7 @@ set-option -g status-attr default
 # Central window list.
 # `#I` = index, `#F` = last window indicator, `#W` = window name
 set-option -g status-justify "centre"
-set-option -g window-status-format "#[bg=colour234] #[fg=colour244]#I#[fg=red]#F#[fg=colour249]#W "
+set-option -g window-status-format "#[bg=colour234] #[fg=colour244]#I#[fg=red] #[fg=colour249]#W "
 set-option -g window-status-current-format "#[bg=red] #[fg=colour231]#I #[bold]#W "
 
 # Left status.