CHILPANCINGO DE LOS BRAVO, MEXICO — Elvira Moreno Abarca’s head barely reaches the shoulder of Roberto Esteban Mateo Martínez, her romantic partner. She fixes her eyes on his, places a hand on his red shirt, lifts and straightens her body, and breathes. The red print of her dress runs down to her ankles. Her feet begin to move to the beat of the live music. It is 5 p.m. in the zócalo, or main square, of Chilpancingo de los Bravo. Jueves de Danzón — Danzón Thursday — has begun. For the latest news & views from every corner of the world, Worldcrunch Today is the only truly international newslett…