By James Mackenzie and Karolina Tagaris ATHENS (Reuters) – Vangelis, the Greek composer whose rousing electronic theme music for the Oscar-winning 1981 film “Chariots of Fire” became one of the most loved movie scores, has died at the age of 79. The law firm representing the composer said he died late on Tuesday, without giving a cause of death. In a post on Twitter, Greek Prime Minister Kyriakos Mitsotakis called Vangelis “a pioneer of the electronic sound.” “He began his long journey on the Chariots of Fire. From there he will always send us his notes,” Mitsotakis wrote. “Ad astra, Vangelis”…