Started work on serialization, refactoring

js/UGraphEntity.js

@@ -0,0 +1,22 @@
+/**
+ * A Graph Entity is an element that can stay directly (as a first child) on the blueprint grid. Those entities are either nodes or links
+ */
+export default class UGraphEntity extends HTMLElement {
+    constructor() {
+        super()
+        /** @type {import("./UEBlueprint").default}" */
+        this.blueprint = null
+    }
+
+    connectedCallback() {
+        this.blueprint = this.closest('u-blueprint')
+        let aDiv = document.createElement('div')
+        aDiv.innerHTML = this.render()
+        this.appendChild(aDiv.firstElementChild)
+    }
+
+    // Subclasses want to rewrite this
+    render() {
+        return ""
+    }
+}