Add Acton nsieve

It's fairly slow and the string formatting is just horrible, but it works!

bench/algorithm/nsieve/1.act

@@ -0,0 +1,23 @@
+#!/usr/bin/env runacton
+
+def nsieve(n: int):
+    count = 0
+    flags = [True] * n
+    for i in range(2, n, 1):
+        if flags[i]:
+            count += 1
+            for j in range(i, n, i):
+                flags[j] = False
+    n_s = ""
+    for j in range(0, (8-(len(str(n)))), 1):
+        n_s += " "
+    c_s = ""
+    for j in range(0, (8-(len(str(count)))), 1):
+        c_s += " "
+    print("Primes up to %s%d %s%d" % (n_s, n, c_s, count))
+
+actor main(env):
+    n = 4 if len(env.argv) < 2 else int(env.argv[1])
+    for i in range(0, 3, 1):
+        nsieve(10000 << (n - i))
+    await async env.exit(0)