Fibonacci, lucas, binomial, factorial

Implemented fibonacci(n), fibonacci2(n) (gives Fibonacci(n) and (n-1), lucas(n), lucas2(n), binomial(n) and factorial(n)

In `src/tests/ntheory/test_ntheory.cpp` the functions that take unsigned longs are required to be imported (ln 12-14) whereas the others do not need to be imported. Any reason why?