Add a random module.

test/random/int_max.wren

@@ -0,0 +1,14 @@
+import "random" for Random
+
+var random = Random.new(12345)
+
+var counts = [0, 0, 0, 0, 0]
+for (i in 1..10000) {
+  var n = random.int(5)
+  counts[n] = counts[n] + 1
+}
+
+for (count in counts) {
+  if (count < 1900) System.print("too few")
+  if (count > 2100) System.print("too many")
+}