1. (20) Write two functions which calculate the n-th value of the fibonacci
   sequence (see page 175, problem 10).  The first calculates the
   value iteratively, the second recursively.

2. (20) Write two functions to calculate the factorial function, one
   iteratively, one recursively.

3. (10) Chapter 14, Programming Project 4.

4. (15) Write a recursive function which will delete all the nodes in a
   linked list.

Make sure these functions are all exercised from your main() function.