This is exactly the same as assignment 1 except that you will use 
merge-sort instead of quicksort. There is no need to read this all
over again.

The files
      /home/www/class/een118/database1.txt
      /home/www/class/een118/database2.txt
      /home/www/class/een118/database3.txt
      /home/www/class/een118/database5.txt
      /home/www/class/een118/database10.txt
      /home/www/class/een118/database20.txt
      /home/www/class/een118/database30.txt
      /home/www/class/een118/database50.txt
      /home/www/class/een118/database100.txt
are databases containing the social security number, first name, last
name, and birth dates of a large number of pretend people. The numbers
1, 2, 3, 5, 10, 20, 30, 50, 100 in the file names indicate how many
thousand entries the files contain.

Your program should be able to read any of those files, store the data
in an array of pointers to suitably designed objects, and sort that array
(correctly) using merge-sort.

They should be sorted into ascending order primarily by last name. When
two people have the same last name, order them by first name. If two people
have both names the same, use their birth dates and put the oldest first.

On the first turn-in date, your programs do not need to be perfect yet.
They will be given a fairly quick preliminary grading so that you get
feedback quickly, and if there is anything seriously wrong you will get
some timely pointers on how to improve it. Of course you will also have
the opportunity to ask questions about problems you are having difficulties
with.

On the second turn-in date (yet to be announced), high quality clear
readable working code will be expected.