Unsupported `array` type in `txamqp.codec` module.

[Ilya]

txamqp seems to be lacking support of the array data type[1].

This type is required to parse envelope of dead-lettered messages[2] as implemented by RabbitMQ (and possibly others). While unconditionally expired messages seem to be rather nice to implement delayed RPC[3].

I am offering you the patch for the `txamqp/codec.py` file that implements array type decode support. The patch is generated against current trunk version of this file.

Cheers.

References:
[1] http://www.amqp.org/sites/amqp.org/files/amqp.pdf "1.2.4 Array" (page 19)
[2] https://www.rabbitmq.com/dlx.html
[3] http://stackoverflow.com/questions/17014584/how-to-create-a-delayed-queue-in-rabbitmq

[Ilya (ilya-o)]

I am also attaching the codec.py file that was used to generate the patch above.

Just in case. :-)