Add is_even and is_odd to math module

test/unit/stdlib/math/math_is_even_odd.c3

@@ -0,0 +1,23 @@
+module math_is_even_odd_tests;
+import std::math;
+import std::io;
+
+macro test(start, ...)
+{
+    $for (var $i = 0; $i < $vacount; $i++)
+        for ($vatype($i) i = ($vatype($i))start; i < 5; i+=2)
+        {
+	    assert(math::is_even(i));
+	    assert(i.is_even());
+
+	    assert(!math::is_odd(i));
+	    assert(!i.is_odd());
+        }
+    $endfor;
+}
+
+fn void! tests() @test
+{
+    test(0, char, ushort, uint, ulong, uptr, usz, uint128);
+    test(-4, ichar, short, int, long, iptr, isz, int128);
+}