Automatic calculation dependency detection

[mikofski]

Currently calculation dependencies have to be entered manually, which is a bit redundant and often leads to errors.

Carousel should automatically detect dependencies by comparing the output arguments to returns from other calculations.

For example:

class MyCalc(Calculation):
    calc1 = CalcParameter(
        formula='f_my_formula',
        args={'data': {'x': 'arg1'}, 'outputs': {'y': 'arg2'}},
        returns=['arg3']
    )
    calc2 = CalcParameter(
        formula='f_my_other_formula',
        args={'data': {'w': 'arg0'}, 'outputs': {'z': 'arg3'}},
        returns=['arg4']
    )

So it's obvious that calc2 depends on calc1 because it uses arg3 for z in f_my_other_formula which is a return from calc1.