/*
 *  call-seq:
 *     dvector.uniq! -> dvector
 *  
 * Same as Dvector#uniq, but modifies the receiver in place.  Returns nil if no changes are made
 * (that is, no duplicates are found).
 *  Removes duplicate elements from dvector.
 *  Deletes the element if there is a later one in the vector that is equal to it.
 *     
 *     a = Dvector[ 1.1, 3.8, 1.7, 3.8, 5 ]
 *     a.uniq!              ->   Dvector[1.1, 1.7, 3.8, 5]
 *     b = Dvector[ 1.1, 3.8, 1.7, 5 ]
 *     b.uniq!              ->   nil
 */ VALUE dvector_uniq_bang(VALUE ary) {