New York Times: The United States and El Salvador said this week that they had settled their differences over compliance with the fine print of a trade agreement that threatened to hold up aid to the small Central American country, but the timing of the dispute has become an embarrassment for Washington. The surge of Central American migrants to the United States over the last few months has been a stark reminder of the poverty and violence they face at home. To some, Washington’s haggling over a program to help…