Add missing newlines after "not_refractory = ..."
Make sure to handle semicolon-separated statements correctly
Fix Exponential Euler integration for equations with only constant terms
Initialize the not_refractory parameter with True
Fix some issues surrounding the use of more complex expressions
(cherry-picked from synapses branch)
Deal with boolean variables correctly by wrapping them in "bool(...)" -- we have to find a more convenient way to handle this
Add tests for refractoriness