Justin Maxwell did exactly what a four-year veteran is supposed to do a week before the Astros’ first official spring training workout for the 2013 season. The center fielder casually shagged fly balls, threw light batting practice and offered up simple tips about a complex game — all with his 4-year-old son. With about 15 Astros participating in informal workouts Saturday at the minor league portion of the team’s Osceola Stadium complex, Maxwell enjoyed the warm, relaxed, sun-filled vibe that is MLB spring training at its best. “You talk to every player and as soon as the season’s over, it’s maybe a week or a couple days before guys want [...]