Elon Musk sought to rally Tesla shareholders around his vision for achieving the electric-vehicle maker’s long-term goal of accelerating a transition to sustainable energy. The Tesla chief executive and other Tesla managers made their pitch Wednesday at an investor event held at the company’s factory near the Texas capital. The presentation, dubbed the company’s “Master Plan Part 3,” was part mission statement and partly a look under the hood at how Tesla tackled various design and engineering challenges and is lowering costs.