Add Stack component for rendering stacked elements

src/components/Stack.js

@@ -0,0 +1,6 @@
+import { $html } from "sigpro";
+import { joinClass } from "../core/utils.js";
+
+/** STACK */
+export const Stack = (props, children) => 
+  $html("div", { ...props, class: joinClass("stack", props.class) }, children);