By Ahmed Eljechtimi and Graham Keeley RABAT/MADRID (Reuters) -Dozens of migrants were pictured lying by a Moroccan border fence, some bleeding and many apparently lifeless, in video showing the aftermath of an attempted mass crossing into a Spanish enclave on Friday in which at least 18 died. Moroccan authorities said the disaster occurred after migrants attempted to breach a fence into the Melilla enclave, with some dying in a crush after what authorities called a stampede, and others falling as they climbed. The Moroccan Association for Human Rights (AMDH) local head Omar Naji said its membe…