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/variables.scss

@@ -135,7 +135,3 @@ $subtitle-sup-size: 15px;
 $breadcrumb-item-color: $primary;
 $checkbox-background-color: #fff;
 $title-color: $violet-3;
-
-@import "~bulma";
-@import "~bulma-divider";
-@import "~buefy/src/scss/buefy";