1998-11-23  Miguel de Icaza  <miguel@nuclecu.unam.mx>

	* src/sheet.h: formula_cell_list *ONLY* exists in the Workbook,
	not on the Sheet.

	* src/sheet.c (sheet_cell_formula_link,	sheet_cell_formula_unlink):
	Keep the formula on the Workbook, not on the Sheet.  Thanks to
	Havoc for reporting these bugs.

	* src/cell.c (cell_set_formula): Use cell_set_rendered_text to
	propery set the error messages.
	(cell_get_text): If value is NULL, use the rendered version of the
	text instead of re-rendering it.