Ability to search by entity type

[philgooch]

A really useful enhancement would be to be able to search by entity type, e.g. have a combo box below the search field to allow one or more of the defined entity types to be selected, in order to limit the search to just these types.

[ajenhl]

This should be easy enough to implement:

• Add an entity type field to forms/display.py EntitySearchForm.
• Modify views/display.py search and search_eatsml to get the entity type from the form and pass it through to lookup_entities.
• Modified the line sets.append(set(Entity.objects.filter(query))) in models/eats_topic_map.py lookup_entities to sets.append(set(Entity.objects.filter(query).filter_by_entity_type(entity_type).
• Add in logic to not include that filter_by_entity_type if no entity_type is supplied.