Operator overloading test

examples/operator_overloading.kl

@@ -0,0 +1,14 @@
+
+Vec3   :: struct;; x: F32; y: F32; z: F32
+"+" :: (a: Vec3, b: Vec3): Vec3 ;; return Vec3{a.x+b.x, a.y+b.y, a.z+b.z}
+
+
+main :: (): int
+  a := Vec3{1,1,1}
+  b := Vec3{2,3,4}
+  c := a + b
+  Assert(c.x == 3)
+  Assert(c.y == 4)
+  Assert(c.z == 5)
+
+  return 0