Homepage: omit youtube embed from short event list
Homepage: link event title to local detail page

This leaves just a small toggle button but feels more natural. Maybe
we should just make the button bigger?
Base template: add container for breadcrumbs

This makes it trivial to add breadcrumb nav by adding the additional
elements inside {% block breadcrumbs %}.

Breadcrumbs can be turned off entirely as on the homepage using an
empty block:

{% block breadcrumbs-container %}{% endblock breadcrumbs-container %}
Events: finish browser hierarchy

* Add breadcrumb nav throughout section
* Add date-based drilldown throughout section
* Add year and month-level listings