A bill to increase Maine’s minimum teacher salary to $40,000 won support in the House of Representatives on Tuesday, likely portending a victory for Democrats and the state teachers union, who have been working since 2014 to enact such a measure. The proposal from Sen. Rebecca Millett, D-Cape Elizabeth, hand-picked over two other similar bills voted down by the Education and Cultural Affairs Committee in March, won 86-56 support in the House.