WASHINGTON (Reuters) - Voters in California and Ohio will decide next week whether to strip state politicians of the right to draw their own legislative district lines, the first public tests of a national effort to increase electoral competition and reduce the power of incumbency. The two ballot initiatives, California's Proposition 77 and Ohio's Issue 4, would transfer the power to set congressional and legislative boundaries to independent panels, robbing state lawmakers of their traditional ability to twist and shape district lines for political advantage. Similar initiatives are in the works in Florida and Massachusetts, and at least a dozen...