WANA, Pakistan (Reuters) - Pakistani forces battled al Qaeda-linked militants Sunday in a fifth day of fighting in a remote tribal region bordering Afghanistan, where several army posts came under rocket attack, witnesses said. Artillery fire boomed in the Shakai area of South Waziristan, 250 miles southwest of Islamabad, where Pakistani forces were trying to flush-out foreign and local militants from their mountain hideouts, witnesses said. "Our houses shook because of the artillery fire all night," said one resident in Wana, the main town of South Waziristan. The army was hitting targets in the Shakai area. Militants fired rockets at...