- Spans were not redrawn when interupted.
- Spans were not recalculated when the blockage was cleared.
- Sorting crashed because the semantics of sheet_remove_cell
  changed to call cell_destroy.

2000-05-08  Jody Goldberg <jgoldberg@home.com>

	* src/sheet.c (sheet_cell_calc_span) : redraw the bounding range when
	  interupting spans.
	(sheet_clear_region) : Respan ranges that were interupted by the
	  cleared region.
	(sheet_cell_remove_simple) : rename from sheet_cell_remove_internal and
	  export.