SETTRIG expression [ , expression ]

   Synopsis:
      Adds a dependent trigger

   Notes:
      A convenient way to create a trigger that launches another Axbasic script
         (or notifies this script's parent task) whenever it fires.
         
      The first expression is the stimulus (a pattern). For triggers, the
         pattern is matched again lines of text received from the world.
      (Axmud automatically assigns its own name to dependent triggers.)
         
      If the second expression is specified, it should be the name of an Axbasic
         script to run immediately (without a parent task) when the trigger
         fires.
      If the second expression is omitted, this script's parent task receives a
         notification when the trigger fires. Axbasic provides several intrinsic
         (built-in) functions for getting information about these notifiacations
         (see the help for NEXTIFACE for more information).
      Also see the help for WAITTRIG.

   Requires:
      If the script is not being run as a task, a SETTRIG statement without a
         second expression (specifying another script to run) is ignored (and no
         error message is generated). Execution continues with the next
         statement.
         
   Examples:
      SETTRIG "The orc kills you"
      SETTRIG "You are ready to cross the bridge!", "cross_bridge"
