MEHTAR LAM, Afghanistan In his first public speech since signing a peace deal with the Afghan government, one of Afghanistan’s most notorious warlords on Saturday called for the Taliban to stop fighting and begin negotiations. “I invite you to join the peace caravan and stop the pointless, meaningless and unholy war,” Gulbuddin Hekmatyar said to a gathering of his followers and Afghan politicians in Laghman province, east of the capital, Kabul. In February the United