This is identical to the last assignment from ECE218 last semester, except that
one requirement has been added: You must be able to delete an entry from the tree.

The file /home/218/database.txt contains 10,000 lines of data. Each line describes
one person: Social security number, birth date (YYYYMMDD), first name, last name,
and zip code.

Here are six unexciting lines from the middle of the file:

    525373469 19630128 Nancy Frankenstein 88539
    525388530 19630228 Darcy Epstein 56906
    525397776 19710519 Frances Cadwallader 88625
    525535897 19361217 Edwin Frogmorton 07004
    525753047 19380123 Alexander Jones 24267
    525780779 19420616 Tom Wilson 39264

You are to write a program that reads this file and stores its information in an 
ordinary Binary Tree. The tree should be ordered on the person's name - primarily 
last name, but when two people have the same last name, order them by first name.

Once your program has constructed the list, it should enter an interactive loop,
taking commands from the user:

FIND firstname lastname
   - display all information about the named person,
     your program must not crash if no such person exists!

PRINT
   - display all information about everyone in the database, in
     alphabetical order based on their names.

ZIP zipcode
   - display the names of all people living in the given zip code

OLDEST
   - print the name and zipcode of the oldest person in the database.

DELETE firstname lastname
   - remove the indicated entry from the tree.
     your program must not crash if no such person exists!

EXIT
   - exit from the program.