Should changing the return Rate type be a breaking change and major version bump

[alecloudenback]

Ref #102

E.g. if previously, zero(curve,10) returned Yields.Rate{Float64, Periodic}(0.05, Periodic(1)) but now returns Yields.Rate{Float64, Continuous}(0.04879016416943205, Continuous())

[alecloudenback]

Argument for "Yes": Output changed and is therefore breaking
Argument for "No": Equivalent rate is returned