Features:

• Added effect.io, which gives intents for representing print and raw_input-style interactions
• The Func intent now accepts _args and *_kwargs to pass through to the function, and which are compared on __eq__, to make testing easier.
• effect.raise_ is a convenience function to raise an exception instance.
• effect.testing.noop is lambda i: None, and is intended to be used in perform_sequence sequences.
• effect.perform_delay_with_sleep is a new performer that performs Delay intents by sleeping.
• The exceptions raised from perform_sequence have more informative output.