WATERVILLE — The 21st annual Maine International Film Festival kicked off Friday night with a screening of “The Bookshop” before a packed audience at the Opera House. The 10-day festival, which typically brings more than 10,000 people to Waterville, screens films at both the Opera House and Railroad Square Cinema. Festival attendees also have the chance to have discussions and dialogue with producers, actors, directors and others in the film industry. The festival is a project of the Maine Film Center.