By Neil Moxley If ever there was an example of a negative being turned into a positive, then Dave Busst is the living embodiment of it. When your claim to fame – in the former Coventry City centre-half’s own words – ‘the worst-ever injury in football,’ there are one of two routes to go down. One is a spiral of self-misery. The other is using it as a force for good – and after over two decades caring for the city’s needy and worthy – it’s fair to say the 56-year-old has taken the latter path. But let’s take you back in time. To April 8, 1996, at Old Trafford when the Sky Blues defender collide…