*procedure
**
UNPACKSTRING
      To unpack the length count and characters in a  string
into a vector, one to a word.
      unpackstring ( string, vector )
      The  length  and characters in the string are unpacked
one to a word into the vector, such that
          string % 0 -> vector ! 0
etc. The string and vector may be coincident ( ie.,  @string
= @vector ) but they may not otherwise overlap.


