/*
 *  call-seq:
 *     dvector.sort                   -> a_dvector 
 *     dvector.sort {| a,b | block }  -> a_dvector 
 *  
 *  Returns a new vector created by sorting _dvector_. Comparisons for
 *  the sort will be done using the <code><=></code> operator or using
 *  an optional code block. The block implements a comparison between
 *  <i>a</i> and <i>b</i>, returning -1, 0, or +1.
 *     
 *     a = Dvector[ 4, 1, 2, 5, 3 ]
 *     a.sort                    -> Dvector[ 1, 2, 3, 4, 5 ]
 *     a                         -> Dvector[ 4, 1, 2, 5, 3 ]
 *     a.sort {|x,y| y <=> x }   -> Dvector[ 5, 4, 3, 2, 1 ]
 */ VALUE dvector_sort(VALUE ary) {