Replace handlebars with string.replace

The html.hbs template does not contain any logic,
so we can replace the lib with good old string.replace calls.
This significantly reduces the bundle size, as we don't have to ship
a full template engine to the client.

Signed-off-by: David Mehren <git@herrmehren.de>

public/js/extra.js

@@ -17,7 +17,6 @@ import markdownitContainer from 'markdown-it-container'
 /* Defined regex markdown it plugins */
 import Plugin from 'markdown-it-regexp'
 
-import handlebars from 'handlebars'
 import 'gist-embed'
 import abcjs from 'abcjs'
 
@@ -669,19 +668,15 @@ export function exportToHTML (view) {
   tocAffix.find('*').removeClass('active').find("a[href^='#'][smoothhashscroll]").removeAttr('smoothhashscroll')
   // generate html via template
   $.get(`${serverurl}/build/html.min.css`, css => {
-    $.get(`${serverurl}/views/html.hbs`, data => {
-      const template = handlebars.compile(data)
-      const context = {
-        url: serverurl,
-        title,
-        css,
-        html: src[0].outerHTML,
-        'ui-toc': toc.html(),
-        'ui-toc-affix': tocAffix.html(),
-        lang: (md && md.meta && md.meta.lang) ? `lang="${md.meta.lang}"` : null,
-        dir: (md && md.meta && md.meta.dir) ? `dir="${md.meta.dir}"` : null
-      }
-      const html = template(context)
+    $.get(`${serverurl}/views/html.hbs`, template => {
+      let html = template.replace('{{{url}}}', serverurl)
+      html = html.replace('{{title}}', title)
+      html = html.replace('{{{css}}}', css)
+      html = html.replace('{{{html}}}', src[0].outerHTML)
+      html = html.replace('{{{ui-toc}}}', toc.html())
+      html = html.replace('{{{ui-toc-affix}}}', tocAffix.html())
+      html = html.replace('{{{lang}}}', (md && md.meta && md.meta.lang) ? `lang="${md.meta.lang}"` : '')
+      html = html.replace('{{{dir}}}', (md && md.meta && md.meta.dir) ? `dir="${md.meta.dir}"` : '')
       const blob = new Blob([html], {
         type: 'text/html;charset=utf-8'
       })