More functions, more nested loops

0-isupper.c Checs for uppercase character 1-isdigit.c Checks for a digit 0 through 9 2-mul.c Multiplies two integers 3-print_numbers.c Prints the numbers, from 0 to 9 4-print_most_numbers.c | Prints the numbers, from 0 to 9, except 2 and 4 | 5-more_numbers.c | Prints 10 times the numbers, from 0 to 14 | 6-print_line.c | Draws a straight line in the terminal | 7-print_diagonal.c | Draws a diagonal line in the terminal | 8-print_square.c | Prints a sqaure | 9-fizz_buzz.c | Prints Fizz-Buzz test | 10-print_triangle.c | Prints a triangle | 100-prime_factor.c| Finds and prints the largest prime factor of the number612852475143 | 101-print_number.c | Prints an integer |