Add tasks for all the new languages

Task/Even-or-odd/Sidef/even-or-odd-1.sidef

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+var n = 42;
+say n.is_odd;       # false
+say n.is_even;      # true

Task/Even-or-odd/Sidef/even-or-odd-2.sidef

@@ -0,0 +1,2 @@
+func is_odd(n)  { n&1 == 1 };
+func is_even(n) { n&1 == 0 };

Task/Even-or-odd/Sidef/even-or-odd-3.sidef

@@ -0,0 +1,2 @@
+func is_odd(n)  { n%2 == 1 };
+func is_even(n) { n%2 == 0 };