Add markdown-it-named-headers and adjust to use Japanese or Chinese

browser/lib/markdown.js

@@ -60,6 +60,14 @@ md.use(math, {
 md.use(require('markdown-it-imsize'))
 md.use(require('markdown-it-footnote'))
 md.use(require('markdown-it-multimd-table'))
+md.use(require('markdown-it-named-headers'), {
+  slugify: (header) => {
+    return encodeURI(header.trim()
+      .replace(/[\]\[\!\"\#\$\%\&\'\(\)\*\+\,\.\/\:\;\<\=\>\?\@\\\^\_\{\|\}\~]/g, '')
+      .replace(/\s+/g, '-'))
+      .replace(/\-+$/, '')
+  }
+})
 // Override task item
 md.block.ruler.at('paragraph', function (state, startLine/*, endLine */) {
   let content, terminate, i, l, token