LONDON / LONG ISLAND,  — Rick Davies, the soulful voice and creative force behind the iconic rock band Supertramp, has died at the age of 81 following a prolonged battle with multiple myeloma, a form of blood cancer. The loss, announced by the band today, marks the end of an era for fans of progressive and pop-rock alike. Born Richard Davies in Swindon, England, in 1944, he co-founded Supertramp in 1969 alongside Roger Hodgson. The group evolved into a defining act of the 1970s — their 1979 album Breakfast in America sold over 18 million copies and earned two Grammy…