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/post_howto.htm

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+<html>␍	<head>␍		<title>Post Flipnote</title>␍		<meta name="uppertitle" content="Post Flipnote">␍		<meta name="postchannelbutton" content="http://flipnote.hatena.com/ds/v2-xx/post/flipnote.post">␍		<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">Posting a Flipnote</div>␍			<div class="news-body">␍				<p>Posting a flipnote is as easy as pressing the button down below and selecting the flipnote you want to upload!</p>␍			</div>␍		</div>␍	</body>␍</html>