C: Exercise 4-3 improved by splitting ascending/descending loop into two...

Improvement to exercise 4-3 using a different type of switchable for loop, with compiler examination. 

Repl: https://replit.com/@pereiradaniel/Improved-asc-desc-for-loop-added-to-existing-project

Git repo: https://github.com/pereiradaniel/beginning_c/blob/master/ch4/exercises/4_3/refactor5.c