port runtime to typescript, move runtime/app.js to runtime.js

src/runtime/utils.ts

@@ -0,0 +1,19 @@
+export function detach(node: Node) {
+	node.parentNode.removeChild(node);
+}
+
+export function findAnchor(node: Node) {
+	while (node && node.nodeName.toUpperCase() !== 'A') node = node.parentNode; // SVG <a> elements have a lowercase name
+	return node;
+}
+
+export function which(event: MouseEvent) {
+	return event.which === null ? event.button : event.which;
+}
+
+export function scroll_state() {
+	return {
+		x: window.scrollX,
+		y: window.scrollY
+	};
+}