By Maria Caspani, Brendan O’Brien and Daniel Trotta (Reuters) – For Irma Garcia and Eva Mireles, teaching fourth graders at Robb Elementary in Uvalde, Texas, was one of the joys of their lives, a vocation dedicated to educating children and keeping them out of harm’s way. Relatives briefed by police said Garcia and Mireles died on Tuesday trying to protect their students after a gunman burst into their classroom, barricaded the doors and opened fire with a semi-automatic rifle. Nineteenth children, aged 9 and 10, and the gunman himself were killed, and multiple others were wounded. Garcia, a m…