WAITACTIVE expression

   Synopsis:
      Waits for an Axmud task to become active

   Notes:
      All Axmud tasks have a property called 'activeFlag'.
      Many tasks don't make use of this property - they are designed to be
         running (when they are added to the current tasklist), or not running
         (when they are removed from it). For those tasks, the 'activeFlag'
         property is always set to a FALSE value.
      Some tasks, however, are designed to run 'in the background', so to speak.
         When their 'activeFlag' property gets set to a TRUE value, the task
         becomes active. When the 'activeFlag' property is returned to a FALSE
         value, the task becomes disactivated and goes back to running in the
         background.
      Precisely how this is implemented can vary from task to task, but any
         running task has an 'activeFlag' property which is set to either TRUE
         or FALSE.

      WAITACTIVE pauses execution of the script until a task matching the
         expression becomes active (i.e. when the task's 'activeFlag' property
         is set to a TRUE value).
      The expression is the name of a task in the current tasklist. It can be a
         task label (e.g. "stat", "status"), a task's formal name (e.g.
         "status_task") or a task's unique name (e.g. "status_task_9").
      If more than one task matches the expression, only the first matching task
         is used.
      If there is no matching task in the current tasklist, the script will not
         resume execution until a matching task has started, and has become
         active.
      See also the help for WAITNOTACTIVE.

   Requires:
      If the script is not being run as a task, the WAITACTIVE statement is
         ignored (and no error message is generated). Execution continues with
         the next statement.

   Examples:
      WAITACTIVE "condition"
      PRINT "I'm back, baby!"
