LONDON (Reuters) – Jailed Russian opposition politician Alexei Navalny said on Thursday that authorities had opened a new criminal case against him for promoting terrorism and extremism, potentially more than doubling his sentence. Navalny, the most prominent domestic critic of President Vladimir Putin, is already serving prison terms totalling 11-1/2 years for fraud, contempt of court and parole violations, all of which he rejects as trumped-up charges intended to silence him. “I am a genius of the underworld. Professor Moriarty is no match for me,” he said sarcastically in a Twitter post, co…