http://www.cstr.ed.ac.uk/projects/festival/. Unlike most drivers, the
festival driver queues incoming commands, rather than overwriting them.
When the queue is full, new commands are discarded.
Supported interfaces:
Required devices:
Supported configuration requests:
| Name | Type | Default | Meaning |
| port | integer | 1314 | The TCP port on which Player should communicate with Festival. |
| libdir | string | "/usr/local/festival/lib" | Festival's library directory. |
| queuelen | integer | 4 | The length of the incoming command queue. |