July 23, 2013 By DAVID W. CHEN and JAVIER C. HERNÁNDEZ   Anthony D. Weiner’s improbable campaign for mayor was engulfed on Tuesday by a new scandal involving explicit online messages, imperiling his political resurrection two years after he resigned from Congress over similar behavior. Mr. Weiner, appearing solemn and a bit worn as he faced more than 100 journalists at a hastily arranged news conference, acknowledged that his habit of sending sexual images and text messages . >>> READ MORE ...