Add tasks for all the new languages

Task/Palindrome-detection/Sidef/palindrome-detection-1.sidef

@@ -0,0 +1 @@
+say "noon".is_palindrome;    # true

Task/Palindrome-detection/Sidef/palindrome-detection-2.sidef

@@ -0,0 +1,3 @@
+func palindrome(s) {
+    s == s.reverse
+}

Task/Palindrome-detection/Sidef/palindrome-detection-3.sidef

@@ -0,0 +1,11 @@
+func palindrome(s) {
+    if (s.len <= 1) {
+        true
+    }
+    elsif (s.first != s.last) {
+        false
+    }
+    else {
+        __FUNC__(s.ft(1, -2))
+    }
+}