Enables translators to easily add localized title, subtitle and description

By adding strings in following format:

```
{% block loc_title %}{% block h1_title %}タイトル{% endblock h1_title %}{% endblock %}
{% block loc_subtitle %}{% block h2_subtitle %}サブタイトル{% endblock h2_subtitle %}{% endblock %}
{% block loc_description %}概要{% endblock %}
```

#1017