Subranges and Array sections

• A ``subrange'' is a triplet subrange of some primitive range, created by a suitable member function, eg

       x.sub(lb, ub, stride) ;
  

  The signature of sub would be

       Range Range :: sub(int, int, int) ;
  

  Subranges inherit the orthogonality properties of their parent primitive range.
• A section of an array is created by passing subranges of the array's range set to a suitable member, eg

      a.sect(x.sub(0, 99, 2), y) ;  // a(0 : 99 : 2, :)
  

  The signatures of `sect' would be

      ArrayInt ArrayInt :: sect(Range x) ;
      ArrayInt ArrayInt :: sect(Range x, Range y) ;
      ...