Chargers get extension to lift blackout

It may be the preseason, but the Chargers already are in midseason blackout-avoidance form. San Diego’s NFL franchise has received a 24-hour extension of the deadline for selling all non-premium tickets to Thursday night’s preseason opener against the Seahawks.  The Chargers have until 10:00 p.m. ET on Tuesday to sell the remaining tickets, which number…