New command-line argument.

I've added the -v command-line argument to print informative comments while
executing.   For example

  $ java -classpath pa1.jar:. main -v LinkedList
  LinkedList.insertAfter(null, 1) failed.
  Can't determine the ADT implemented by LinkedList

  $

The jar file and the assignment page have been updated.  Let me know if you
have any questions.