Version 6.4.0, 2012-04-12

  Switch from (system) readline to (embedded) editline (libedit).

Version 6.3.2, 2012-03-28

  Support coordinate ranges for delete, shift, raise commands.
  Multiple-step commands undone atomically.

Version 6.3.1, 2012-03-26

  Support xchange command.
  Display new coordinates of shifted/raised nodes for subsequent raise/shift.

Version 6.3, 2012-03-21

  Support opt course boxes.

