Update Coq proofs for number theory examples and prove admitted lemma along the way.

...ograms/gcd/gcd_WP_EuclideanAlgorithm_WP_parameter_gcd_1.v

...s/gcd_bezout/gcd_bezout_WP_GcdBezout_WP_parameter_gcd_1.v

...me_numbers_WP_PrimeNumbers_WP_parameter_prime_numbers_4.v

...me_numbers_WP_PrimeNumbers_WP_parameter_prime_numbers_5.v

...me_numbers_WP_PrimeNumbers_WP_parameter_prime_numbers_6.v

...bers/knuth_prime_numbers_WP_PrimeNumbers_exists_prime_1.v