Richard Lutz heads north-  on a mission. The Gaelic names tumble from the tongue- Carn a Coire Boidheach, Sgurr Gaibhre, Liathach and Schiehallion. Those and about 280 others that collectively are the Munro mountains of Scotland. As Nigel said last month: ‘Climbing them all isn’t a hobby- it’s a sickness.’ I went up my 99th…