[Int] add is-prime and expmod

lib/Int.pod

@@ -35,4 +35,23 @@ codepoint number and converting it the corresponding character.
 
 Does an integer division, rounded down.
 
+=head2 expmod
+
+	multi sub    expmod (Int:D: Int $y, Int $mod) returns Int:D
+	multi method expmod (Int:D: Int $y, Int $mod) returns Int:D
+
+Returns the given C<Int> raised to the C<$y> power within modulus C<$mod>.
+
+=head2 is-prime
+
+	multi sub    is-prime (Int:D: Int $tries = 100) returns Bool:D
+	multi method is-prime (Int:D: Int $tries = 100) returns Bool:D
+
+Returns C<True> if this C<Int> is known to be a prime, or is likely to be a
+prime based on a probabalistic Miller-Rabin test. C<$tries> is the maximal
+number of iterations the test is allowed to do. 
+
+Returns C<False> if this C<Int> is known not to be a prime, or is unlikely to be
+a prime after probabalistic testing.
+
 =end pod