ThinkProgress writes, One year ago today, Trayvon Martin — an unarmed 17-year-old boy on his way home from 7-11 — was shot and killed by George Zimmerman. The murder trial is scheduled to begin this June. A separate hearing may be held in April to determine whether Florida’s controversial “Stand Your Ground” law gives Zimmerman immunity. While nothing can make up for the events of February 26, 2012, many people have responded to the tragedy with compassion, courage and strength. Here are some of the most inspiring things that have happened over the last year. 1. 192 colleagues of Trayvon Martin’s mother…