Review from Robert, and nits

*** 67,78 ****
       1.   If none of -c, -E, -P, or -S appears in the argument list (that is,
            linking is attempted), the shadow compilers will not be invoked.
            This is because the objects built with that compiler which would be
            linked have been previously discarded.
  
!      2.   If an option of the form -o filename was provided, it will be
!           replaced by two options of the form -o tempfile
  
       3.   If the option -o was not provided, -o tempfile will be added to the
            end of the argument list used to invoke the shadow compilers.
       When shadow compilation is in effect, cw writes to standard error each
       compiler's standard error output following its argument list.  Messages
--- 67,78 ----
       1.   If none of -c, -E, -P, or -S appears in the argument list (that is,
            linking is attempted), the shadow compilers will not be invoked.
            This is because the objects built with that compiler which would be
            linked have been previously discarded.
  
!      2.   If the -o filename option was provided, with or without a separating
!           space, it will be replaced with -o tempfile
  
       3.   If the option -o was not provided, -o tempfile will be added to the
            end of the argument list used to invoke the shadow compilers.
       When shadow compilation is in effect, cw writes to standard error each
       compiler's standard error output following its argument list.  Messages