BOSTON — Travel guru Rick Steves is set to tour Massachusetts in support of a pro-marijuana ballot question. Steves is host of the PBS series “Rick Steves’ Europe” and a longtime advocate of easing marijuana laws. Steves plans to make three stops across the state next month to stump for the question, which would legalize the recreational use of marijuana. In a statement, Steves said there are many reasons to end the prohibition on pot, including redirecting money from criminals and into state coffers.