blog: fixed setting of title: title was not show when embedded was True, but this is always the case (articles.html template is always shown in base.html). A new "blog_page" boolean is set when articles.html is the main page displayed (i.e. blog posts are not embedded in an other page like events), and use to display the title, fixing the originally intented behaviour. fix 298

{% macro form(action='', class='') %}
<form method="post" action="{{action}}" {{ {'class': class}|xmlattr }} {{kwargs|xmlattr}} >
    {% if csrf_token is defined %}
        <input type="hidden" name="csrf_token" value="{{csrf_token}}">
    {% endif %}
    {{ caller() }}
</form>
{% endmacro %}