Class constructor/init method should not be an instance method

[kyleect]

class Foo {
  fn init(arg) {
    print "Foo.init(" + arg + ")";
    this.field = "init";
  }
}

let foo = Foo("one"); // out: Foo.init(one)
foo.field = "field";

let foo2 = foo.init("two"); // out: Error: No method "init" on instance