Topic/plat 6640 part3

This just adds demos for caplet stripping. These use the test framework (for conveniences) but are not tests as such. There is one class, `CombinedCapletStrippingResults`, which used purely as a helper class for these demos, which is not independently tested.  
When run these demos produce a lot of formatted numbers that can be pasted into Excel (or elsewhere) to produce plots. In particular, they are used to produce plots in the caplet stripping white paper I am writing.