By Thomas Escritt BERLIN (Reuters) – With Twitter in disarray since the world’s richest person took control of it last week, Mastodon, a decentralised, open alternative from privacy-obsessed Germany, has seen a flood of new users. “The bird is free,” tweeted Tesla mogul Elon Musk when he completed his $44 billion acquisition of Twitter. But many free-speech advocates reacted with dismay to the prospect of the world’s “town square” being controlled by one person and started looking for other options. For the most part, Mastodon looks like Twitter, with hashtags, political back-and-forth and tec…