Tributes have been flooding in for Alex Trebek, the much-loved US quiz show host who has died aged 80 following a pancreatic cancer diagnosis.The Canadian-born presenter passed away surrounded by friends and family at his California home, a spokesperson said.Among those to offer their condolences was Canadian prime minister Justin Trudeau, who said "we have lost an icon"."Almost every night for more than three decades, Alex Trebek entertained and educated millions around the world, instilling in