Adding DiscreteVolatilityFunction
Added 'volatlity' classes to the branch
Improving test coverage
Merge branch 'refs/heads/topic/PLAT-6697' into topic/PLAT-6701
added FunctionalSurface
Added weightSensitivity to BasisFunctionAggregation
Adding VolatilitySurfaceProvider
Added getNumberOfParameters method to ParameterizedFunction (this affects several classes and tests).
Added ParameterizedVolatilitySurfaceProvider
Added tests