The developer behind Easton Town Center is planning a large expansion of residences around the venerable shopping center, with investment likely totaling more than $250 million. Georgetown Co. has reached a financial arrangement with Columbus, through which it promises to create 500 jobs and help fund a revival of the nearby Linden neighborhood while receiving a break on property taxes. The 10-year, 100 percent property-tax abatement could save the developer $68 million over 37 years, said Steve…