Get all of the history for a name or namespace.
    Returns a dict keyed by block heights, paired to lists of changes (see namedb_history_extract)

def namedb_get_history( cur, history_id, offset=None, count=None, reverse=False ):
    """
    Get all of the history for a name or namespace.
    Returns a dict keyed by block heights, paired to lists of changes (see namedb_history_extract)
    """
    # get history in increasing order by block_id and then vtxindex
    history_rows = namedb_get_history_rows( cur, history_id, offset=offset, count=count, reverse=reverse )
    return namedb_history_extract( history_rows )