2000-05-06  Michael Meeks  <michael@helixcode.com>

	* src/eval.c (handle_cell_range_deps): Add 3D dependency support.
	(cb_single_hash_to_list, cb_range_hash_to_list): Re-arrange handling of
	where the list is collated. (do_deps_destroy): update.
	(cell_drop_dependencies): remove cretinism here.
	(drop_cell_range_dep, handle_cell_single_dep): return on NULL deps structure.

	* src/sheet-style.c (sheet_style_attach): enable cache trash avoidance code.

	* src/sheet.c (sheet_cell_remove_internal): short circuit for NULL
	deps.

	* src/expr.c (expr_rewrite): update to handle workbook case.

	* src/eval.c (workbook_deps_destroy): update for speed.
	(sheet_deps_destroy): split body into (do_deps_destroy): here.

	* src/workbook.c (workbook_delete_sheet): destroy the sheet's
	dependencies here as well; very silly. (workbook_do_destroy): destroy
	deps of all sheets up front.