+ renable the 'display-panes' command

  - the 'move-window' command has been remapped to the 'w' key
+ let tmux panes to be resized with the arrow keys

  - the 'bind -r' option allows the arrow keys to be toggled more than
    once in a short sequence of time after the 'Ctrl-a' command prefix.

  - The short sequence of time is now defined to be within 500ms.  This
    is the 'repeat-time' command adjustment.