Feature: Action System (#298)

* Add Action System

- Add keyboard test
- Add context menu label
- Add PanelComponent

* Show context menu items based on actions

* Add render action feature

- Replace bringForward etc buttons with action manager render functions

* Move all property changes and canvas into actions

* Remove unnecessary functions and add forgotten force update when elements array change

* Extract export operations into actions

* Add elements and app state as arguments to `keyTest` function

* Add key priorities

- Sort actions by key priority when handling key presses

* Extract copy/paste styles

* Add Context Menu Item order

- Sort context menu items based on menu item order parameter

* Remove unnecessary functions from App component

src/actions/actionDeleteSelected.tsx

@@ -0,0 +1,19 @@
+import React from "react";
+import { Action } from "./types";
+import { deleteSelectedElements } from "../scene";
+import { KEYS } from "../keys";
+
+export const actionDeleteSelected: Action = {
+  name: "deleteSelectedElements",
+  perform: elements => {
+    return {
+      elements: deleteSelectedElements(elements)
+    };
+  },
+  contextItemLabel: "Delete",
+  contextMenuOrder: 3,
+  keyTest: event => event.key === KEYS.BACKSPACE || event.key === KEYS.DELETE,
+  PanelComponent: ({ updateData }) => (
+    <button onClick={() => updateData(null)}>Delete selected</button>
+  )
+};