Panel to Review U.S. Tax Code By Warren Vieth, Times Staff Writer WASHINGTON — A presidential commission today launched what it promised would be a top-to-bottom review of the U.S. tax code, but acknowledged that it might make more sense to modify the income tax than to try to replace it. Members of the president's advisory panel on federal tax reform said all options were on the table, including proposals to replace personal and corporate income taxes with variations on a national sales tax. "The president is committed to major tax reform, to real tax reform, to something more than...