Add tasks for all the new languages

Task/Arithmetic-Complex/Sidef/arithmetic-complex.sidef

@@ -0,0 +1,13 @@
+var a = 1:1;                # Complex(1, 1)
+var b = 3.14159:1.25;       # Complex(3.14159, 1.25)
+
+[   a + b,                  # addition
+    a * b,                  # multiplication
+    -a,                     # negation
+    1 / a,                  # multiplicative inverse
+    ~a,                     # complex conjugate
+    a.abs,                  # abs
+    a.sqrt,                 # sqrt
+    b.re,                   # real
+    b.im,                   # imaginary
+].each { |c| say c }