Changes by: Jason Hickey (jyh at cs.caltech.edu)
Date: 2006-04-24 21:30:04 -0700 (Mon, 24 Apr 2006)
Revision: 9126
Log message:

      Forgot tho check this in.
      Ignore empty command lines in rules.  This means that such rules like the following
      should again work.
      
      .SCANNER: foo
         @