When Ryan Gainer was diagnosed with autism as a toddler, he was nonverbal, and his family all learned sign language to communicate with him. But after the southern California boy learned how to speak at around age four, he was a “ball of energy” who never stopped talking, his older sister Rachel said.He loved saying “hi” to neighbors and strangers alike, and as a young teen was known as the student who greeted everyone with a “good morning” and a smile.Ryan’s family spoke of his early years and bright presence two weeks after his life was cut short at age 15, when sheriff…