Disable highlight spans after a search

```
"<span class="search_hit">conjug</span>_espagnol"
```

should be

```
"conjug_espagnol"
```

See http://galerie.microalg.info/profgra:peda:conjug_espagnol?s[]=conjug.

Maybe try https://www.dokuwiki.org/plugin:nohighlight.
