keeping cols rows in segmented arrays.

- Large speed improvement in exit by operating on the entire sheet rather than
  cell by cell.

- Large speed improvement in Col/Row auto-fills.  they're still too damn slow
  and we use too much memory, but its a start.

- Insert/delete/Shift rows/cols now correctly adjusts references to and from
  the region.

- Code in place to restructure 'copy'

- A few minor dialog adjustments, some from me, some from the mailing list.