Add tasks for all the new languages

Task/Pi/Sidef/pi.sidef

@@ -0,0 +1,26 @@
+func pi(callback) {
+    var (q, r, t, k, n, l) = (1, 0, 1, 1, 3, 3);
+    loop {
+        if ((4*q + r - t) < n*t) {
+            callback(n);
+            static _dot = callback('.');
+            var nr = 10*(r-n*t);
+            n = (int((10*(3*q + r)) / t) - 10*n);
+            q *= 10;
+            r = nr;
+        }
+        else {
+            var nr = ((2*q + r) * l);
+            var nn = int((q*(7*k + 2) + r*l) / (t*l));
+            q *= k;
+            t *= l;
+            l += 2;
+            k += 1;
+            n = nn;
+            r = nr;
+        }
+    }
+}
+
+STDOUT.autoflush(1);
+pi(func(digit){ print digit });