Undo for
- Renaming a sheet
- Inserting current date/time
- Simplify wording for translators.

2000-01-09  Jody Goldberg <jgoldberg@home.com>

	* src/commands.c (cmd_insert_cols) : Be kinder to translators.
	(cmd_insert_rows) : Ditto.
	(cmd_rename_sheet) : Implement.
	(cmd_set_date_time_{undo,redo,destroy}) : Implement.
	(cmd_set_date_time) : Implement.

	* src/workbook.c (sheet_label_text_changed_signal) : Use
	  cmd_rename_sheet.
	(insert_at_cursor) : Delete.
	(insert_current_time_cmd) : Use cmd_set_date_time.
	(insert_current_date_cmd) : Use cmd_set_date_time.