The Post reports today that a new experimental arts festival is planned for July 2006. The Capital Fringe Festival will be a 10-day showcase of local and visiting performers working in theater, dance, music and other disciplines. According to festival founder Damian Sinclair, director of marketing for Woolly Mammoth Theatre Company and a relative newbie to D.C., Capital Fringe will be concentrated downtown along the Seventh Street corridor in 20 venues, including theaters, galleries, lobbies,…