A walk through Mad Square Park on Monday morning revealed a welcome sight – the fences around the beloved and sorely missed Shack Shack kiosk at the southeast corner of the park have come down, revealing progress to date on the renovation of the Shake Shack grounds and seating areas. For Shake Shack addicts, who have sorely missed the mouth-watering hamburgers and extra-thick shakes over these many months while the renovation was under way, this is the best possible omen for the coming spring and summer.  To check on the progress thus far, watch this Flatiron Hot! sneak-peak video …