A power couple in the real estate business is promoting a contest to name a mixed-use project on the fourth side of the square that features luxury condos with a bird’s-eye view of downtown Gainesville. Bev and Tim Knight launched the contest this week to come up with a name for the $16 million project — a 15,000-square-foot building with street level retail and restaurants, and 40 condos above — in the heart of downtown. The development by Knight Commercial Real Estate is one of three recently announced downtown projects with a total investment of $53 million.