message_name        params expected                  returns
----------------------------------------------------------
build               list(type cursor_x, cursor_y)    0, non-0  (for true/false)
                    type=object ype
                    cursor_x & y = poxition on pad
  - sent by build window to objects to see if they can build a specific type
    of unit.

convoy_deployed     li_g1_objref                     0
                    (pointer to convoy) 
  - sent by convoy to factory when it is sent somewhere, factory clears it's
    build pad and build pad window.


on                  0                                0
  - sent by triggers, switches, etc to objects they are attached to when
    they turn on.  The user can modify this message, but on is the default

off                 0                                0
  - sent by triggers etc to objects they are attached to when
    they turn off.  The user can modify this message, but off is the default

set_course         start_object                      0, non-0 (not ACKed/ACKed)
  - sent by factories to objects when they built

                   
reached             path_object_reached              0
  - signals an object that a new path point has been reached