Governor Carlson says he plans to call a special legislative session in September to deal with the Minnesota Twins request for a publicly-funded ballpark. Carlson says he bellieves the Twins will leave if lawmakers don't approve funding before October...when the team can opt out of its Metrodome lease. Minnesota Public Radio's Bill Wareham reports: When the regular legislative session ended without a floor vote on a stadium plan legislative leaders pledged to study the issue over the summer and vote on it early in the '98 session. The governor says that's too late. Carlson says he came away from a meeting with members of the Pohlad family last week convinced the t