With less than two weeks to go in the 1997 legislative session the proposed stadium for the Minnesota Twins is in deep trouble -- in part because the project's cost seems to have escalated precipitously. The latest figures from the Metropolitan Sports Facilities Commission put the price tag at $506-million dollars -- up more than $150-million dollars from February estimates. Commission officials say they didn't miscalculate. Rather...they say changes to the deal keep adding new expenses. Minnesota Public Radio's Bill Wareham reports: Back in February stadium supporters were pitching a $350-million dollar ballpark for the Twins. Last week the figure was $439-mil