MICHAEL BURNHAM — Westward pioneers halted their wagons in Portland, OR 150 years ago, but today’s politicians and planners aim to make recession- battered Portland the starting point for green-economy trailblazers. Mayor Sam Adams and General Electric Co. executives are forging a first-of-its-kind partnership that will include retrofitting drafty buildings with energy-saving technologies and helping local startups sell their clean-technology products abroad.