A simulation for randomly placing k indistinguishable items into n distinct boxes,
 so that no box remains empty.

 main variables:
 n = number of boxes
 k = number of items (0 for as many as it takes for all boxes to have at least one item)
 t = number of trials

 parameters:
 s = 1 to show boxes (warning: may take a long time for large numbers!), 0 to hide boxes
 v = 1 to show status messages, 0 to hide messages

 output:
 returns a list where each element is the number of items needed to fill all boxes for a trial,
 or if all k items are used before each box is filled, the element is zero instead.