feat: port Hatena server to Python 3

* Update server-side database and dynamic resource code for Python 3
* Preserve existing Flipnote, UGO, NTFT, CSS, localization, and Hatena assets
* Port Flipnote upload and movie endpoints
* Update front page UGO menu generators
* Preserve existing database and sample Flipnote data
* Add regression tests for database operations and binary formats
* Add server resource loading tests
* Maintain compatibility with the original DSi Flipnote Studio protocol

hatenadir/ds/v2-xx/help/info.htm

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+<html>␍	<head>␍		<title>Info</title>␍		<meta name="uppertitle" content="Info">␍		<link rel="stylesheet" type="text/css" href="http://flipnote.hatena.com/css/ds/common.css">␍	</head>␍	<body>␍		<div class="container">␍			<div class="title" align="center">pbsds's Hatena Server</div>␍			<div class="news-body">␍				<p>This server is a proof of concept server. There's not much functionality yet because it's in early stages. Please enjoy your stay.</p>␍			</div>␍		</div>␍	</body>␍</html>