“The hearing of a case in public may be, and often is, no doubt, painful, humiliating, or deterrent both to parties and witnesses, and in many cases, especially those of a criminal nature, the details may be so indecent as to tend to injure public morals, but all this is tolerated and endured, because it is felt that in public trial is to be found, on the whole, the best security for the pure, impartial, and efficient administration of justice, the best means for winning for it public confidence and respect”