Add example for complex numbers

examples/complex

+# A simple weighted automaton with complex numbers as weights.
+
+C^X
+
+a: { a: 1 + 0i, b: 0 + 1i, c: 1 + 1i }
+b: { a: 1i, b: 1, c: 1i + 1 }
+c: { a: 0, b: 0, c: 0 }

examples/complex.out

+Block 0: a, b
+Block 1: c