Add timestamp support.

scripts/primes.rhai

@@ -1,5 +1,7 @@
 // This script uses the Sieve of Eratosthenes to calculate prime numbers.
 
+let now = timestamp();
+
 const MAX_NUMBER_TO_CHECK = 10_000;     // 1229 primes <= 10000
 
 let prime_mask = [];
@@ -24,3 +26,4 @@ for p in range(2, MAX_NUMBER_TO_CHECK) {
 }
 
 print("Total " + total_primes_found + " primes.");
+print("Run time = " + now.elapsed() + " seconds.");