Howard Dean spent part of the morning today explaining what one network television interviewer called his "explosive" speech Monday night telling supporters he would not give up...... Dean referred to his frenetic, shouting appearance before supporters in Iowa after the caucus results became known, a performance that led NBC's Katie Couric to tell him this morning, "Some people watching feared you might implode." "Do you think things got a little out of control and you got a little over the top?" she asked Dean on the Today Show. "Can you explain that?" Dean replied, "Thirty-five hundred young people showed up...