Function fibo::fibo_rec

pub fn fibo_rec<T: Index>(n: T, m: T) -> T

Compute the n-th Fibonacci number modulo m using recurssion (F(n) <= F(n-1) + F(n-2)). Since the recurrsion computes the same Fibonacci numbers multiple times, it is very slow to compute. The computation time is O(F(n)) = O(φ^n). Maybe n = ~40 is the maximum value that this function can compute the Fibonacci number.