Improve build times

* Fix bulma/buefy being imported many (many !!!) times

* Remove javascript-time-ago because date-fns pretty much does the same
thing

* Make sure languages are loaded asynchronously

Signed-off-by: Thomas Citharel <tcit@tcit.fr>

js/src/components/Editor.vue

@@ -552,8 +552,6 @@ export default class EditorComponent extends Vue {
 }
 </script>
 <style lang="scss">
-@import "@/variables.scss";
-
 $color-black: #000;
 $color-white: #eee;