cutting and pasting a reference originally in one book into another.

2000-01-11  Jody Goldberg <jgoldberg@home.com>

	* src/workbook.c (workbook_detach_sheet) : Even books with only 1
	  sheet can have inter-sheet references.  think inter-book...
	(workbook_can_detach_sheet) : Delete we can always detach a sheet.

	* src/expr.c (cellref_relocate) : We only need to range check
	  references that are changing.

	* src/workbook.c (workbook_expr_relocate) : Copying to the same
	  logical cell in another sheet is still a copy.

	* ./src/eval.c (cell_queue_recalc_list) : Handle cross workbook
	  depends correctly.

	* src/eval.c (sheet_get_intersheet_deps) : Delete it is now unnecessary.
	(dependency_data_destroy) : invalidate dangling intersheet
	  dependancies.