Make package more integrated with FinanceModels

[alecloudenback]

v0.5 updated the package to be compatible in a basic way, but left a few design questions unresolved:

• is it a bad idea to return a tuple instead of an array?
• How should these models be thought of w.r.t. FinanceModels. Are they subtypes of FinanceModels or do they need to be converted/wrapped?
  • Thought: individual scenario outcomes can be used to create a corresponding singular FinanceModel object, but can also be wrapped in a (to be developed) MonteCarlo object such that MonteCarlo valuations can be performed.
  • Is YieldCurve the right function to create an indivual instantiation?