By Adam Bloodworth The first English-speaking tourist to visit this once-dangerous Medellin neighbourhood, Adam Bloodworth finds a Colombia with a new sense of purpose. Photography by Omar Portella Oscar is crouching on an upturned breeze block, resting in the afternoon sun. Behind him, an eight thousand foot drop towards the city of Medellin. On the way down the hill, tree top canopies cluster like ink blots, contrasting with the dense houses. The view stretches hundreds of miles across Colombia. We had trekked uphill in the sweltering heat, climbing outdoor staircases threaded between settle…