#2 Seat mapping without categories

[SabbeRubbish]

When in Seat Mapping mode, and an event with no categories is selected, whenever a block is selected for this event, the following warning occurs:

Warning: mysql_data_seek() [function.mysql-data-seek]: Offset 0 is invalid for MySQL result index 27 (or the query data is unbuffered) in includes\seat_mapping.inc on line 303

This will be fixed later.