Topic/plat 6658

* Extended SmileInterpolatorSABR into **SmileInterpolatorSABRWithExtrapolation** such that SABR takes left and right extrapolations as **SmileExtrapolationFunctionSABRProvider**. 
* Two choices are available for the extrapolators, **ShiftedLogNormalExtrapolationFunctionProvider** and **BenaimDodgsonKainthExtrapolationFunctionProvider**.
* Smoothness of the extrapolations at cut-offs is tested in **SmileInterpolatorSABRWithExtrapolationTest**.
* Extended SABR-specific methods (and also only right extrapolation can be applied to these methods), CouponIborInArrearsReplicationMethod and CapFloorIborInArrearsSABRCapGenericReplicationMethod, into **CouponIborInArrearsSmileModelReplicationMethod** and **CapFloorIborInArrearsSmileModelCapGenericReplicationMethod** which take **InterpolatedSmileFunction** constructed from GeneralSmileInterpolator.
* Consistency between the old methods and the new methods (in terms of the right extrapolation with SABR) is confirmed in the test class **CapFloorIborInArrearsSmileModelCapGenericReplicationMethodTest**
Can you comment on what is going on here? It seams like; if the smile model is Hagan's original SABR formula, use the 3-point fits, otherwise (i.e. some other SABR variant) use a global fit. The effect of this, is that SmileInterpolatorSABR doesn't behave like an interpolator (i.e. it fits all the data points)  when a VolatilityFunctionProvider other than SABRHaganVolatilityFunction is passed to the constructor.