feat(smt2/parser.yy): Support equality between formulas
feat(smt2/parser.yy): Support equality between formulas

dreal/dreal4,soonho-tri/dreal4,dreal/dreal4,soonho-tri/dreal4,dreal/dreal4,soonho-tri/dreal4,dreal/dreal4,soonho-tri/dreal4