McLaren will break cover on its 2019 challenger on Valentine's Day – February 14 for all you non-romantic types – and the teasing has already begun in earnest. Carlos Sainz and Lando Norris will hope the MCL34 can help them reap rich rewards after McLaren's struggles of last year, but excitement is building ahead of the new season, with more elements of the 2019 livery revealed on social media…