Changed old <aside> syntax to use {% sidenote %} tag

scripts/aside.js

@@ -2,11 +2,18 @@ var jsdom = require('jsdom'),
     crypto = require('crypto'),
     util = require('util');
 
-hexo.extend.filter.register('after_post_render', function(data) {
-    data.content = data.content.replace(/<aside>([^\r]+?)<\/aside>/mg, function(match, content) {
-        var id = crypto.createHash('sha256').update(content).digest('hex');
-        return util.format('<label for="%s" class="sidenote-number margin-toggle"></label>', id) +
-            util.format('<input type="checkbox" class="margin-toggle" id="%s">', id) +
-            '<span class="sidenote">' + content + "</span>";
-    });
-});
+hexo.extend.tag.register('sidenote', function(args, content) {
+    var id = crypto.createHash('sha256').update(content).digest('hex');
+    return util.format('<label for="%s" class="sidenote-number margin-toggle"></label>', id) +
+        util.format('<input type="checkbox" class="margin-toggle" id="%s">', id) +
+        '<span class="sidenote">' + hexo.render.renderSync({text: content, engine: 'md'}).replace(/<\/?p>/g, "") + "</span>";
+}, {ends: true});
+
+// repeated because adding several conditionals turns 2 4-line
+// functions into a single hard-to-follow 10-line function
+hexo.extend.tag.register('marginnote', function(args, content) {
+    var id = crypto.createHash('sha256').update(content).digest('hex');
+    return util.format('<label for="%s" class="margin-toggle">&#8853;</label>', id) +
+        util.format('<input type="checkbox" class="margin-toggle" id="%s">', id) +
+        '<span class="marginnote">' + hexo.render.renderSync({text: content, engine: 'md'}).replace(/<\/?p>/g, "") + "</span>";
+}, {ends: true});