add option to pass in alpha parameter (action precision) to Agent() constructor directly
added unit test to control.py for testing new alpha input to Agent() feature
added internal method of _sample_action_test() to Agent() that returns the action marginals (for use in unit-test)
This should close Issue #81, see https://github.com/infer-actively/pymdp/issues/81
alphaparameter (action precision) toAgent()constructor directlycontrol.pyfor testing newalphainput to Agent() feature_sample_action_test()toAgent()that returns the action marginals (for use in unit-test) This should close Issue #81, see https://github.com/infer-actively/pymdp/issues/81