get_data() should return all indexes

[gmrza]

At the end of the get_data() method in presentations.py, there is a comment that only index 0 is being returned and possibly all should be returned. This is indeed the case for presentations that have multiple indexes. The .get('0', {}) at the end of line 95 probably should be removed.
This will result in a "dictionary of dictionaries" being returned, however it will allow the user to retrieve other indexes than just the first one.