#10 Multiple choices in node parameters

[Dominic Letourneau]

It could be interesting to add multiple choices to node
parameters. They could be stored in the node
description like :

@parameter_name SAMPLE_RATE
@parameter_type int
@parameter_value 44100:22000:11000:8000
@parameter_description Sample rates of the sound card!

This could offer a simpler interface (multiple choices
in the GUI) for users that do not know what are valid
parameter values.