add sidebar and infinite scroll

src/Sidebar.js

@@ -0,0 +1,18 @@
+import React, {Component} from 'react';
+import './Sidebar.css';
+
+export function Sidebar(props) {
+    return (
+        <div className={props.content ? 'sidebar-on' : ''}>
+            <div className="sidebar-shadow" onClick={props.do_close} />
+            <div className="sidebar">
+                <p>
+                    <a onClick={props.do_close}>×</a>
+                    &nbsp;{props.title}
+                </p>
+                <hr />
+                {props.content}
+            </div>
+        </div>
+    );
+}