SPRINGFIELD — At the Statehouse, former Gov. Patrick J. Quinn popularized the line, “let the will of the people be the law of the land.”Today, it was a panel of Senate lawmakers, facing a constitutional change arguably inspired by current Gov. Bruce Rauner, who grappled with the concept.A Democrat-controlled subcommittee acted on several other amendments this morning, approving one that would give Illinois a graduated income tax by altering the constitution and removing the flat rate citizens currently …