Tabular coach reports can now be generated for playlists as well as topics

Is this on the right track to resolve #2808?
This will throw an AssertionError if the entry is malformed.

However, if the entry_id is incorrect, we will have a KeyError in the line above.

Perhaps best to do:
```
new_item = get_node_cache()[entry_type].get(entry['entity_id'], [None])[0]
if new_item:
    prepared.append(new_item)
```