ORLANDO, Fla. — As public education has evolved from a one-size-fits-all system to one where families are empowered to choose the environment that best fits their child, everyone has been a winner: Students, parents, educators, entrepreneurs, and even public school districts. That was the message of John F. Kirtley, founder and chairman of Step Up For Students, to the roughly 1,000 people who attended the non-profit’s Navigating New Horizons conference this week.