Merged PR 16: Transform every single class components into functional component

This improve greatly the performance and the code cleaning.
It allows us to separate the inseparable class methods into modules functions

src/Components/App/App.tsx

@@ -0,0 +1,79 @@
+import React, { useEffect, useState } from 'react';
+import './App.scss';
+import { MainMenu } from '../MainMenu/MainMenu';
+import { ContainerModel } from '../../Interfaces/ContainerModel';
+import Editor, { IEditorState } from '../Editor/Editor';
+import { LoadState } from './Load';
+import { LoadEditor, NewEditor } from './MenuActions';
+import { DEFAULT_CONFIG, DEFAULT_MAINCONTAINER_PROPS } from '../../utils/default';
+
+// App will never have props
+// eslint-disable-next-line @typescript-eslint/no-empty-interface
+interface IAppProps {
+}
+
+export const App: React.FunctionComponent<IAppProps> = (props) => {
+  const [isLoaded, setLoaded] = useState<boolean>(false);
+
+  const defaultMainContainer = new ContainerModel(
+    null,
+    DEFAULT_MAINCONTAINER_PROPS
+  );
+
+  const [editorState, setEditorState] = useState<IEditorState>({
+    configuration: DEFAULT_CONFIG,
+    history: [{
+      MainContainer: defaultMainContainer,
+      SelectedContainer: defaultMainContainer,
+      SelectedContainerId: defaultMainContainer.properties.id,
+      TypeCounters: {}
+    }],
+    historyCurrentStep: 0
+  });
+
+  useEffect(() => {
+    const queryString = window.location.search;
+    const urlParams = new URLSearchParams(queryString);
+    const state = urlParams.get('state');
+
+    if (state === null) {
+      return;
+    }
+
+    fetch(state)
+      .then(
+        async(response) => await response.json(),
+        (error) => { throw new Error(error); }
+      )
+      .then((data: IEditorState) => {
+        LoadState(data, setEditorState, setLoaded);
+      }, (error) => { throw new Error(error); });
+  });
+
+  if (isLoaded) {
+    return (
+      <div>
+        <Editor
+          configuration={editorState.configuration}
+          history={editorState.history}
+          historyCurrentStep={editorState.historyCurrentStep}
+        />
+      </div>
+    );
+  }
+
+  return (
+    <div className='bg-blue-100 h-full w-full'>
+      <MainMenu
+        newEditor={() => NewEditor(
+          setEditorState, setLoaded
+        )}
+        loadEditor={(files: FileList | null) => LoadEditor(
+          files,
+          setEditorState,
+          setLoaded
+        )}
+      />
+    </div>
+  );
+};