make simple indicator not light dependent

[kjohnsen]

Make LightDependentProtein a subclass of Protein. Need function for synapse source: ng in Protein and light agg ng in LightDependentProtein

make constructor functions include option for simple or light_dependent, e.g.,

def jgcamp7f(light_dependent=False):
    if light_dependent:
        return LDGECI(**params)
    else:
        return SimpleGECI(**params)
        
gcamp = jgcamp7f(light_dependent=[True|False])

[kjohnsen]

#39